Germany is planning a new law giving authorities the right to look at private messages and fingerprint children as young as 6, the interior minister said on Wednesday after the last government gathering before a national election in September.
Ministers from central government and federal states said encrypted messaging services, such as WhatsApp and Signal, allow militants and criminals to evade traditional surveillance.
"We can't allow there to be areas that are practically outside the law," interior minister Thomas de Maiziere told reporters in the eastern town of Dresden.
Militant attacks in France, Britain and Germany have prompted European governments to tighten up on surveillance of suspected militants. Britain has proposed forcing messaging services to let authorities access encrypted communications.
Among the options Germany is considering is "source telecom surveillance", where authorities install software on phones to relay messages before they are encrypted. That is now illegal.
Austria is also planning laws to make it easier to monitor encrypted messages as well as building out a linked network of cameras and other equipment to read vehicle licence plates.
Last December's lorry attack on a Berlin Christmas market, in which 12 were killed and Germany's struggle to integrate thousands of refugees, have put security high up the political agenda before an election in which German Chancellor Angela Merkel is seeking a fourth term in office.
Ministers also agreed to lower the age limit for fingerprinting minors to 6 from 14 for asylum seekers.
Bavarian interior minister Joachim Herrmann, a Merkel ally whose south-eastern state is the entry point for many refugees fleeing war in the Middle East, said on June 3 he wanted security services to be allowed to monitor children.
That proposal encountered strong opposition in Germany, where the memories of spying in the Communist and Nazi run deep.
"Children are victims of extremism," said Social Democrat family affairs minister Katharina Barley, who said authorities should be protecting children not spying on their friends.
Ministers also agreed to improve communication between the many different regional and national police and investigation agencies in the highly decentralized country.