Serbia's ambassador to NATO has jumped to his death from a multi-storey carpark in Brussels airport, officials have said.

Serbian authorities said they were investigating Wednesday's incident, which was witnesses by several other diplomats.

Branislav Milinkovic, 52, was attending a conference of NATO foreign ministers, but officials did not make any connection between the meeting and his suicide.

"We are shocked and we are investigating all circumstances" surrounding the ambassador's death, said a Serbian Foreign Ministry official who asked not to be named.

"We have no clues about what could prompt Milinkovic to do that. He was a good man," the official said.

Anders Fogh Rasmussen, NATO's secretary-general, said that he was "deeply saddened by the tragic death of the Serbian ambassador", who was highly respected, said an alliance spokesperson.

Belgian authorities said that they were sure the death was a suicide, and so would not be investigating further.

"It was indeed a suicide," said Ine Van Wymersch of the Brussels prosecutor's office.

The Serbian Foreign Ministry praised Milinkovic as a distinguished diplomat and jurist who would be "remembered as a skilled diplomat, an intellectual and a noble man".

Milinkovic was appointed ambassador to NATO in 2009 but had already been based in Brussels since 2004 as an envoy from the now defunct state union of Serbia and Montenegro.

A former author and activist opposed to the authoritarian regime of Serbia's former president Slobodan Milosevic, Milinkovic was outgoing, had a warm sense of humour and worked to keep good ties with ambassadors from other former Yugoslav countries, according to diplomats and acquaintances.

The ambassador is survived by his wife and son.

Source: Agencies