INTERVIEW-Serbia must accept Kosovo to join EU - Ahtisaari

* Serbia should start dealing with Kosovo institutions

* EU should have common stance on Kosovo

PRISTINA, June 16 (Reuters) - Serbia must face reality and start dealing with Kosovo institutions if it wants to join the European Union, Martti Ahtisaari, an architect of Kosovo's independence plan said on Tuesday.

Last year Kosovo declared independence after nine years of United Nations stewardship, but the pro-Western government in Belgrade does not recognise it and refuses to deal with elected Kosovo Albanian officials.

"To get Serbia into the EU they have to learn to live with a neighbour that is an independent country such is Kosovo," Ahtisaari, a Nobel prize winner, told Reuters in an interview.

He said Serbia should turn away from the past and look to establish cooperation with Kosovo to move forward.

"I don't think any country in the world can actually develop properly ... if it doesn't honestly take a look at the past and recognize that things went wrong," he said.

Serbia has set EU membership as a key priority, but the 27-nation bloc says it will not allow Serbia to progress in its bid while fugitive war crimes suspect Ratko Mladic remains at large. Belgrade lost control of Kosovo in 1999, following a 78-day NATO bombing campaign to halt Albanian civilians from being killed during a two-year counter-insurgency war.

Albanians, who make up 90 percent of the population in Kosovo, and 120,000 Serbs remain divided along ethnic lines.

Ahtisaari, who had convinced Serbian strongman Slobodan Milosevic to accept NATO's terms for ending the bombing, disagrees with analysts who say the partition of Kosovo would be the best solution for long lasting peace.

More than half of Kosovo Serbs live in scattered enclaves in southern Kosovo. The rest live north of the river Ibar that is linked with Serbia.

As for Kosovo, it cannot sign agreements with the EU until it is recognised by all members states.

Ahtisaari said the EU needs to work to agree a common stance for Kosovo. He said he was "very disappointed by the behaviour" of five EU members - Spain, Slovakia, Greece, Cyprus and Romania - that have not recognised Kosovo. (Edited by Ivana Sekularac and Matthew Jones)