Croatia on Saturday announced an unprecedented spike in the arrival of migrants on a long, dangerous journey towards western Europe as the continent's worst post-World War II refugee crisis showed no sign of abating.

With many of the people fleeing war and misery flocking towards Germany, a new poll showed Chancellor Angela Merkel's popularity at home has been hit by her policy of openness.

The U.N. refugee agency on Thursday opens a new 1,000-bed camp, equipped with rows of toilets and showers, wifi and chargers, on the Greece-Macedonia border for thousands of people on the move from the Aegean to western Europe.

The makeshift stopover facilities near the small town of Idomeni in northern Greece aim to offer temporary shelter and facilities including health care to the streams of refugees from war and persecution, ANA news agency said.

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.

Bulgaria began on Thursday deploying up to 1,000 troops to buttress its southeastern border with Turkey as hundreds of migrants remained stranded for a third day on the Turkish side, a senior official said.

"We have triggered a plan for the start of the step-by-step deployment of up to 1,000 troops along the whole Bulgarian-Turkish border (within the next week)," interior ministry chief of staff Georgy Kostov said.

The French prime minister was set to meet EU officials in the refugee pinch point of Calais on Monday as increasingly urgent efforts to deal with migration into Europe exposed divisions across the continent.

France is expecting several million euros more in aid from Brussels, a government source said, to help deal with the thousands of migrants and refugees camped out in "The Jungle" around the northern port, hoping to reach Britain.

Bulgaria's army stepped in on Tuesday to buttress the southwestern border with Macedonia, which has been hit in recent days by an unprecedented influx of migrants.

Twenty-five soldiers and light armored vehicles will be deployed at Bulgaria's four border checkpoints with Macedonia, a defense ministry operations and training deputy chief told public BNR radio.

At least 2,000 more migrants flooded overnight into Serbia in a desperate journey to try and go on to Hungary, the door into the European Union, a U.N. official said Monday.

At least 7,000 people -- mostly refugees from the brutal war in Syria -- have been registered so far in the last days in overwhelmed Serbia as Europe's worst refugee crisis in half a century rapidly worsens.

Some 2,000 mostly-Syrian refugees spent a rainy night stranded in no-man's land between Greece and Macedonia as hundreds more began arriving Saturday on their way to western Europe.

The refugees and migrants, who have been there since Thursday, spent the night sleeping on the ground despite heavy rain and temperatures which fell sharply during the night.

Macedonian riot police on Friday fired stun grenades to drive back thousands of mostly Syrian refugees stuck in no-man's land between Greece and Macedonia, the latest flashpoint in Europe's escalating migrant crisis.

At least eight people were hurt near the Greek border village of Edomeni as the police in riot gear beat the migrants back with truncheons and threw the stun grenades, devices that produce a blinding flash of light and a huge noise to disorient their targets.

Bulgaria said Friday it was ready to dispatch its armed forces to secure its southwestern borders with Greece and Macedonia against any fresh influx of refugees.

The announcement came after Macedonia declared a state of emergency and closed its border with Greece because of large numbers of migrants trying to cross.