The main Blace border crossing into Macedonia was closed at 1700 local time (1500 GMT) on Wednesday, with the country saying it could not cope with the refugee influx.

Dennis McNamara of the UNHCR: "Very hard call"

But sources in Skopje now say the border was only closed briefly in a gesture to highlight the huge numbers of refugees it is obliged to accept.

The Former Yugoslav Republic of Macedonia has reassured the United Nations refugee agency (UNHCR) that it will continue to take refugees.

Refugees are queuing up on the Serbian side of the border

And the interior minister told the UNHCR special envoy for former Yugoslavia and Albania, Dennis McNamara, it was the Yugoslav side of the border which was closed.

But the UNCHR is still keen to know what happened to the 1,000 Albanians who were turned back into Kosovo.

Macedonia has warned that it will still allow in only as many ethnic Albanian refugees as third countries can evacuate.

Moves to transfer thousands of refugees from Macedonia to Albania begin on Sunday, with 6,000 going to new camps at Korce in the south east.

The UNHCR estimates more than 210,000 Muslim refugees have already fled to Macedonia as a result of the conflict in Kosovo - equivalent to one tenth of the Macedonian population.

Paul Wood in Skopje: Terrible situation in the camps

The numbers being airlifted out of Macedonia - between 1,000 and 2,000 each day - are currently dwarfed by the numbers arriving, which reached 10,000 on a single day this week.

So far, a total of about 30,000 refugees have been transferred to third countries.

Tit-for-tat

BBC Correspondent in Skopje Paul Wood says the border closure was triggered by Wednesday's World Bank summit not coming up with as big an aid package as Macedonia hoped for.

Just hours before the closure, international donors pledged $250m to Macedonia at the Paris meeting intended to provide a rapid response to the danger to Macedonia's fragile economy.

On Wednesday night, 1,000 refugees in the no-man's-land between Serbia and Macedonia were pushed back by Macedonian troops all the way to Serb territory.

They cannot now be seen by correspondents based in Macedonia and it is not known where they are now.

One report quotes witnesses saying there are currently 3,000 Kosovars waiting on the Serbian side.