German police fired water cannons Wednesday at demonstrators protesting coronavirus restrictions in Berlin's government district, after crowds ignored calls to wear masks and keep their distance from one another in line with pandemic regulations.

As the cannons soaked protesters outside the landmark Brandenburg Gate, police in riot gear moved through the crowd carrying away some participants. Some demonstrators threw fireworks and flares in response as police helicopters hovered overhead.

Germany on Tuesday called on Turkey to end a "cycle of detente and provocation" in the Mediterranean, after Ankara's decision to redeploy a research ship at the centre of tensions with Greece over energy and maritime rights.

Berlin police on Saturday boosted security in the German capital, with barricades put up at French sites including the embassy, after the attacks in Paris that left at least 128 people dead.

"We have adjusted our protection measures overnight," a police spokeswoman told AFP, although she would not give details.

German intelligence warned Tuesday that the number of Islamic extremists in the country had increased sharply in recent months and expressed serious concern that they were recruiting among refugees.

The Office for the Protection of the Constitution (BfV), Germany's domestic security watchdog, said the number of radical Salafists had surged to 7,900 in September from 7,500 in June, and that many were trying to lure asylum-seekers into their ranks.

Germany's interior minister on Monday urged Europe to pick up refugees directly from crisis regions, to help them bypass traffickers who charge huge sums for dangerous journeys to the continent.

"I suggest we agree on a generous quota in which we take refugees from crisis regions to Europe without allowing people smugglers to profit from it," said Thomas de Maiziere at a press conference in Berlin, adding that he was expressing a personal view.

Austrian Chancellor Werner Faymann and German Vice Chancellor Sigmar Gabriel on Saturday called for United Nations countries to contribute an extra five billion euros ($5.65 billion) in aid for refugees living in camps in Lebanon and Jordan.

"We have to help countries where the misery is so great that people are going on the road," Gabriel said, in reference to the tens of thousands of migrants -- many of them Syrian refugees -- who have headed to Europe in recent months.

Thousands of migrants sought their way through a chaotic maze of rumor and proliferating border controls in the western Balkans on Saturday.

In the latest chapter in the EU's escalating refugee crisis, Croatia, Hungary and Slovenia tussled over how to cope with a wave of refugees desperate to reach northern Europe.

An Iraqi man with a jihadist background who stabbed a German policewoman before officers shot him dead in Berlin was presumed to have "acted alone", prosecutors said Friday.

Rafik Mohamad Yousef, 41 -- who had done jail time for a 2004 Berlin assassination plot against former Iraqi prime minister Iyad Allawi -- had a history of aggressive and unstable behavior, recently threatening a judge and other public officials.

Hungary sealed its border with Serbia on Tuesday to stem the massive influx of refugees as Germany slammed the "disgraceful" refusal of other EU countries to accept more migrants after 22 died in yet another shipwreck.

Budapest's move came after Austria and Slovakian authorities followed Germany's lead in reimposing border controls, a further body blow to Europe's cherished passport-free Schengen zone as the EU's border agency said more than half a million migrants had been counted at the bloc's borders so far this year.

Germany said it was reinstating border controls on Sunday as Europe's top economy admitted it could no longer cope with a record influx of refugees.

The announcement came on the eve of a key EU meeting on the crisis, with interior ministers set to lock horns over a controversial plan to spread migrants across the continent.