UNHCR said Macedonian authorities closed the main Blace border crossing with Yugoslavia and may have turned back refugees fleeing violence in Kosovo.
Polish troops are heading for Albania to help to protect a Nato centre that is part of humanitarian operations for Kosovo.
France wants Nato to halt its bombing campaign against Yugoslavia if Belgrade begins withdrawing its troops from Kosovo and agrees to allow refugees to return.
Austrian border authorities turned away a group of 37 ethnic Albanians trying to enter the country illegally yesterday. They were sent back to Italy.
The Dutch Prime Minister, Wim Kok, said his country was prepared to admit more refugees than the 2,000 originally agreed as it had become apparent they were putting too much pressure on neighbouring countries.
The Spanish Prime Minister, Jose Maria Aznar, will visit Moscow next week for talks about the conflict.