BELGRADE/TIRANA (Reuters) - Serbia summoned the Albanian ambasssador on Wednesday to protest at an incendiary flag-flying stunt at an international soccer match that caused a brawl on the pitch and set back hopes for detente between the Balkan neighbours.

Tuesday's Serbia-Albania Euro 2016 qualifier - at which Albanian fans were barred due to tensions between the two countries - was called off when a remote-controlled plane flew a the flag of "Greater Albania" above the field, sparking a brawl that forced the Albanian players to flee.

With the countries trading accusations of xenophobia and extremism, a visit by Albanian Prime Minister Edi Rama to Belgrade next week, that was meant to mark a new chapter in their troubled history, looked at risk of being cancelled.

Relations between Serbia and Albania have long been hostile and hit their lowest point during a war in the former Serbian province of Kosovo in the late 1990s when NATO, concerned about the "ethnic cleansing" of Albanians, deployed airstrikes against Serbian forces.

Kosovo declared independence in 2008, but Belgrade refuses to recognise it, saying the territory, which has a majority Albanian population, is a heartland of the Serbian nation.

Serbia's foreign minister blamed the Albanian prime minister's brother for the drone stunt, with some media reporting that Olsi Rama had been arrested in the VIP stands of the Belgrade stadium with the remote control in his hands.

Olsi denied that and, on Wednesday, a group of Albanian soccer fans said they were behind the incident. The Serbian government and media were livid.

"It was clear they came with the plain and obvious intention to provoke their hosts," Serbian Prime Minister Aleksandar Vucic told reporters. He told the Serbian daily Vecernje Novosti that "Albanian extremists" wanted to portray Serbia as intolerant.

Belgrade summoned Albanian Ambassador Ilir Bocka to protest. "Serbia is working diligently on nurturing good relations with its neighbours, from whom it expects the same approach and it will not tolerate such provocations," the foreign ministry said in a statement.

Albania, however, said Serbia was to blame.

"Hospitality, this sacred asset of all Balkan peoples, was trodden on like never before, in an anti-sporting and xenophobic atmosphere," Foreign Minister Ditmir Bushati told a news conference.

Asked if Rama's visit to Belgrade would go ahead, Bushati replied: "We stick to our objective, as we do to our policy of good neighbourly relations. However, depending on developments, this remains an open issue."

Belgrade's diplomatic corps was dragged into the dispute when Serbian Foreign Minister Ivica Dacic was quoted as saying that several Albanian fans, including Rama's brother, had managed to enter the stadium with the help of Western diplomats.

EU and US envoys denied any involvement.

The Albanian prime minister's brother, who returned to Albania on the team's plane, said he had been "taken aside" by Serbian police during the melee but not arrested. "I've never used a drone in my life, only bought my son a toy helicopter," said Olsi Rama, who has joint Albanian and U.S. nationality.

A photograph posted on the Facebook page of an Albanian soccer fan group showed men posing with what a "quadcopter" similar to the drone used at the match.

Under the caption "Deeds, not just words," one of the men, identified as Agron Sadiku, wrote: "This was not my idea, but that of my uncle's son, Egzon Feri. We never believed it would be done so successfully. I am very happy about it."

There were celebrations on the streets of Albanian-populated towns across the Balkans after Tuesday's match. "Greater Albania" - the area respresented by the flag flown in the stadium - covers Albania, Kosovo and parts of Serbia, Montenegro, Macedonia and Greece claimed by Albanian nationalists.

A Serbian player plucked the flag from the air, several Albanian players reacted angrily, and the pitch was invaded by several dozen Serbian fans. Fans threw flares and seats as the Albanian players raced from the pitch to the tunnel. The match was abandoned at 0-0.

European soccer's governing body UEFA is investigating and has yet to aportion blame or impose any sanctions. UEFA President Michel Platini called the incident "inexcusable".