An official warned the spill posed a "severe threat" to sea life and water quality as China's latest environmental crisis spread off the shores of Dalian, once named China's most livable city.
"I've been to a few bays today and discovered they were almost entirely covered with dark oil," said Zhong Yu with environmental group Greenpeace China, who spent the day on a boat inspecting the spill.
"The oil is half-solid and half liquid and is as sticky as asphalt," she told The Associated Press by telephone.
The oil had spread over 165 square miles (430 square kilometers) of water five days since a pipeline at the busy northeastern port exploded, hurting oil shipments from part of China's strategic oil reserves to the rest of the country. Shipments remained reduced Wednesday.
State media has said no more oil is leaking into the sea, but the total amount of oil spilled is not yet clear.
Greenpeace China released photos Wednesday of inky beaches and of straw mats about 2 square meters (21 square feet) in size scattered on the sea, meant to absorb the oil.
Fishing in the waters around Dalian has been banned through the end of August, the state-run Xinhua News Agency reported.
"The oil spill will pose a severe threat to marine animals, and water quality, and the sea birds," Huang Yong, deputy bureau chief for the city's Maritime Safety Administration, told Dragon TV.
At least one person died during cleanup efforts. A 25-year-old firefighter, Zhang Liang, drowned Tuesday when a wave threw him from a vessel, Xinhua reported.
China Oil Spill
AnIn a handout picture released by Greenpeace on July 21, 2010 and taken on July 20, 2010 shows an activist surveying oil spill damage on a beach at the port of Dalian, Liaoning province. Chinese authorities have closed several beaches and an island resort near the major port of Dalian as they try to clean up an oil spill that has affected crude shipments, state media said on July 21. NO SALES NO ARCHIVE RESTRICTED TO EDITORIAL USE NO MARKETING NO ADVERTISING AFP PHOTO/HO/GREEPEACE/JIANG HE (Photo credit should read Jiang He/AFP/Getty Images)
In a handout picture released by Greenpeace on July 21, 2010 and taken on July 20, 2010 layers of oil cover rocks and the sea on the coast at the port of Dalian, Liaoning province. Chinese authorities have closed several beaches and an island resort near the major port of Dalian as they try to clean up an oil spill that has affected crude shipments, state media said on July 21. NO SALES NO ARCHIVE RESTRICTED TO EDITORIAL USE NO MARKETING NO ADVERTISING AFP PHOTO/HO/GREEPEACE/JIANG HE (Photo credit should read Jiang He/AFP/Getty Images)
In this Tuesday, July 20, 2010 photo, firemen work on a burnt-out oil storage facility in Dalian, in northeast China's Liaoning province. Crude oil started pouring into the Yellow Sea off a busy northeastern port after a pipeline exploded late last week, sparking a massive 15-hour fire. The government says the slick has spread across a 70-square-mile (180-square-kilometer) stretch of ocean. (AP Photo) ** CHINA OUT **
In this Tuesday, July 20, 2010 photo, Chinese firefighters are seen on boats amongst the an oil spill near the coast of Dalian in northeast China's Liaoning province. Crude oil started pouring into the Yellow Sea off a busy northeastern port after a pipeline exploded late last week, sparking a massive 15-hour fire. The government says the slick has spread across a 70-square-mile (180-square-kilometer) stretch of ocean. (AP Photo)**CHINA OUT**
In this photo released by Greenpeace, a firefighter who was submerged in thick oil during an attempt to fix an underwater pump is brought ashore by his colleagues in Dalian, China on Tuesday, July 20, 2010. Crude oil started pouring into the Yellow Sea off a busy northeastern port after a pipeline exploded late last week, sparking a massive 15-hour fire. The government says the slick has spread across a 70-square-mile (180-square-kilometer) stretch of ocean. (AP Photo/Jiang He, Greenpeace) ** NO SALES NO ARCHIVE **
In this photo released by Greenpeace, the oil covered hand of a firefighter who was overwhelmed by the thick oil spill while attempting to fix an underwater pump is seen after he is pulled ashore by his colleagues in Dalian, China on Tuesday, July 20, 2010. Crude oil started pouring into the Yellow Sea off a busy northeastern port after a pipeline exploded late last week, sparking a massive 15-hour fire. The government says the slick has spread across a 70-square-mile (180-square-kilometer) stretch of ocean. (AP Photo/Jiang He, Greenpeace) ** NO SALES NO ARCHIVE **
In this photo released by Greenpeace, a firefighter who was submerged in thick oil during an attempt to fix an underwater pump is brought ashore by his colleagues in Dalian, China on Tuesday, July 20, 2010. Crude oil started pouring into the Yellow Sea off a busy northeastern port after a pipeline exploded late last week, sparking a massive 15-hour fire. The government says the slick has spread across a 70-square-mile (180-square-kilometer) stretch of ocean. (AP Photo/Jiang He, Greenpeace) ** NO SALES NO ARCHIVE **
In this photo released by Greenpeace which shows oil washed ashore near the port of Dalian, China on Tuesday, July 20, 2010. Crude oil started pouring into the Yellow Sea off a busy northeastern port after a pipeline exploded late last week, sparking a massive 15-hour fire. The government says the slick has spread across a 70-square-mile (180-square-kilometer) stretch of ocean. (AP Photo/Jiang He, Greenpeace) ** NO SALES NO ARCHIVE **
In this photo released by Greenpeace, a firefighter who was submerged in thick oil during an attempt to fix an underwater pump is brought ashore by his colleagues in Dalian, China on Tuesday, July 20, 2010. Crude oil started pouring into the Yellow Sea off a busy northeastern port after a pipeline exploded late last week, sparking a massive 15-hour fire. The government says the slick has spread across a 70-square-mile (180-square-kilometer) stretch of ocean. (AP Photo/Jiang He, Greenpeace) ** NO SALES NO ARCHIVE **
In this photo released by Greenpeace, a firefighter rushes to aid his colleague who ran into trouble amid thick oil cover as they attempted to fix an underwater pump in Dalian, China on Tuesday, July 20, 2010. Crude oil started pouring into the Yellow Sea off a busy northeastern port after a pipeline exploded late last week, sparking a massive 15-hour fire. The government says the slick has spread across a 70-square-mile (180-square-kilometer) stretch of ocean. (AP Photo/Jiang He, Greenpeace) ** NO SALES NO ARCHIVE **
Officials, oil company workers and volunteers were turning out by the hundreds to clean blackened beaches.
"We don't have proper oil cleanup materials, so our workers are wearing rubber gloves and using chopsticks," an official with the Jinshitan Golden Beach Administration Committee told the Beijing Youth Daily newspaper, in apparent exasperation.
"This kind of inefficiency means the oil will keep coming to shore. ... This stretch of oil is really difficult to clean up in the short term."
But 40 oil-skimming boats and about 800 fishing boats were also deployed to clean up the spill, and Xinhua said more than 15 kilometers (9 miles) of oil barriers had been set up to keep the slick from spreading.
China Central Television earlier reported an estimate of 1,500 tons of oil has spilled. That would amount roughly to 400,000 gallons (1,500,000 liters) - as compared with 94 million to 184 million gallons in the BP oil spill off the U.S. coast.
China's State Oceanic Administration released the latest size of the contaminated area in a statement Tuesday.
The cause of the explosion that started the spill was still not clear. The pipeline is owned by China National Petroleum Corp., Asia's biggest oil and gas producer by volume.
Friday's images of 100-foot-high (30-meter-high) flames at China's second largest port for crude oil imports drew the immediate attention of President Hu Jintao and other top leaders. Now the challenge is cleaning up the greasy plume.
"Our priority is to collect the spilled oil within five days to reduce the possibility of contaminating international waters," Dalian's vice mayor, Dai Yulin, told Xinhua on Tuesday.
But an official with the State Oceanic Administration has warned the spill will be difficult to clean up even in twice that amount of time.
Some locals said the area's economy was already hurting.
"Let's wait and see how well they deal with the oil until Sept. 1, if the oil can't be cleaned up by then, the seafood products will all be ruined," an unnamed fisherman told Dragon TV. "No one will buy them in the market because of the smell of the oil."
Associated Press researcher Yu Bing in Beijing contributed to this report.