Bulgaria accepts Kosovo statehood

All three are neighbours of Serbia and a joint statement on Thursday prompted a sharp warning from Belgrade that they could not count on good relations.

Sofia said it did not expect ties to suffer but one report said a Bulgarian lorry was pelted with rocks in Serbia.

One hundred Bulgarian intellectuals accused the government of betraying "our Serbian brothers".

Why Serbia's neighbours recognise Kosovo

They described Kosovo as a "criminal state" and said recognising it was "a time bomb for our national security".

Prime Minister Sergei Stanishev said Bulgaria would establish diplomatic relations with Kosovo and open an embassy.

"Bulgaria's interests are to have maximum guarantees to preserve peace and stability in the region," he said.

He said the strongest guarantee was to have international engagement in Kosovo involving Nato, the UN and the EU.

In a separate development, the Bulgarian government announced it would allow US planes and service personnel to enter its airspace during a Nato summit next month.

Up to 18 military planes and 500 troops will be allowed to fly over Bulgaria.

Bulgaria joined Nato in 2004 and the EU in 2007.