A police spokesman said Slovenia would only accept migrants "from countries where there are armed battles". "Over the past days more and more people are arriving for whom we have reason to believe that they are economic migrants," spokesman Drago Menegalija said in a written statement to Reuters.

"We have formally announced to Croatia that we will return a group of economic migrants. We have not yet received a response from the Croatian side."

The United Nations said before that Serbia and Macedonia have begun limiting the passage of migrants across their borders to Syrians, Iraqis and Afghans, turning back Africans and Asians. "As of 6 p.m. yesterday evening Serbia started turning back (to Macedonia) all but Syrians, Iraqis and Afghans," UNHCR spokeswoman Melita Sunjic said. "Macedonia closed the border around 3 a.m and some 100 people remained stranded in no-man's land."

A senior police source in Macedonia, who declined to be named, said Skopje had acted after European Union member Slovenia, further along the migrant path, had told countries in the region that it would start doing the same. "They will turn back all others on the basis they are economic migrants," the official said.

Syrians, Iraqis and Afghans make up the majority of the hundreds of thousands of migrants trekking across the Balkans in the hope of reaching western and northern Europe, mainly Germany and Sweden.

Reuters