Mr Hatoyama supports plans to screen foreigners rigorously

Justice minister Kunio Hatoyama said the man was a "friend of a friend" who was involved in a bomb attack on Bali.

He produced no evidence to back up his claim, but said it showed the need for stricter checks on overseas visitors.

Later he appeared to backtrack, stressing he had not met the man and could not verify his friend's claims.

'Rights violation'

From 20 November almost all foreign visitors and overseas workers will be photographed and fingerprinted as they enter the country.

The measures have already proved controversial, with Amnesty International labelling the system as discriminatory and "a violation of basic human rights".

But Mr Hatoyama used the story of the al-Qaeda member to argue that the threat of terrorism justified the new measures.

"My friend's friend is a member of al-Qaeda. I have never met him, but I heard that two or three years ago he came to Japan several times," he told a press conference.

"The fact is that such foreign people can easily enter Japan. In terms of security, this is not a preferable situation."

The minister also claimed his friend had warned him of the Bali bombing - although there have been two major terrorist attacks on the Indonesian island in recent years and he did not specify which one he was referring to.

Later, Mr Hatoyama cast doubt on all of these claims, saying he had been "unclear and misleading".

He denied he had been warned of any attack on Bali before it had happened.

"I myself am not a friend of anyone who is thought to be a member of [al-Qaeda] and I don't know them personally. I can't verify the authenticity of what my friend said."

Japanese officials plan to check foreigners' fingerprints against international and domestic crime databases to root out potential terrorists and people with criminal records.