BERLIN - The leaders of Germany and France will meet in Berlin on Monday to seek a unified stance on efforts to tackle the biggest migrant crisis since World War II, as hundreds more people poured into Serbia in a desperate bid for a better life.

At least 2,000 more migrants entered Serbia overnight from Macedonia, which has declared a state of emergency over the massive numbers pressing into the country from the Greek border.

They are trying to reach Hungary, a member of the EU's open-border Schengen agreement, which has already registered over 100,000 asylum seekers this year and plans to finish its anti-migrant fence on the Serbian border by the end of August.

Hours ahead of the talks with French President Francois Hollande, German Chancellor Angela Merkel condemned "vile" violent protests against refugees, as anti-migrant sentiment reared its head over the weekend in the eastern city of Heidenau.

"The chancellor and the entire government condemn the violent rampages and the aggressively xenophobic atmosphere in the strongest terms," Merkel's spokesman Steffen Seibert told reporters after the clashes between police and far-right thugs protesting the opening of a new centre for refugees.(AFP)