* Serbia racing to clinch EU accession talks
* Under pressure to regulate relations with Kosovo
* PM says Serbia must define its "real borders"
By Matt Robinson
BELGRADE, March 7 (Reuters) - Serbian Prime Minister Ivica Dacic told Serbs on Thursday they had been lied to that "Kosovo is ours", the latest sign of an historic U-turn by Belgrade as it races to clinch membership talks with the European Union.
Serbia does not recognise Kosovo but is under pressure to improve relations with its former province if the EU is to give the green light to accession talks and send a vital message of stability to much-needed foreign investors.
Dacic, who was an aide to late strongman Slobodan Milosevic when Serbia went to war with NATO over Kosovo but is now in talks with its ethnic Albanian leadership, said Serbia had to finally define its "real borders".
"For 10 years, Kosovo was taboo. No one could officially tell the truth," he wrote in the Serbian weekly NIN. "Tales were told; lies were told that Kosovo is ours."
But today, he said, "the Serbian president cannot go to Kosovo, nor the prime minister, nor ministers, nor the police or army. Serbs can only leave Kosovo. That's how much Kosovo is ours and what our constitution and laws mean there."
Kosovo declared independence with Western backing in 2008, almost a decade after NATO bombs wrested control of the majority-Albanian territory from Milosevic to halt a brutal counter-insurgency war by his forces.
The country of 1.7 million people has since been recognised by more than 90 states, but struggles with a de facto ethnic partition between its Albanian majority and a small Serb pocket in the north propped by Belgrade.
NATO still has 6,000 troops in Kosovo to contain tensions.
That northern, Serb pocket of territory is now at the centre of EU-mediated talks between Dacic and his Kosovo counterpart, former guerrilla commander Hashim Thaci, that resume on March 20 in Brussels.
Though it pledges never to recognise Kosovo as independent, Dacic's coalition government has offered to recognise the authority of Thaci's government over the north, but in return wants autonomy for the Serbs living there.
Thaci fears this will only cement the partition.
In a report last month, the Brussels-based International Crisis Group think-tank said Serbia had "crossed a threshold" and that the two sides had never been closer to resolving the dispute over the Serb north.
The EU wants a deal by mid-April, when the European Commission is due to issue a report on progress in the Kosovo talks. The bloc will then decide whether to open accession talks in June.
Serbia's fellow ex-Yugoslav republic and wartime foe Croatia is due to become the EU's 28th member on July 1.
Serbia is unlikely to join before 2020, but accession talks would provide a boost to its struggling economy and stimulate reforms.
Dacic's text was published in NIN to mark the tenth anniversary next week of the assassination of reformist Prime Minister Zoran Djindjic, who took power with the 2000 ouster of Milosevic but was shot dead in 2003 by a group of former elite paramilitaries and drug smugglers.
The killing slammed the brakes on Serbia's recovery from the war and sanctions of Milosevic's disastrous 13-year rule.
"Ten years later, Serbia has yet to solve the problems that burdened Djindjic's government. It still does not know where its borders are, over what territory it really has sovereignty," Dacic wrote.
"I was part of a government that tried to resolve the question of Kosovo by war. Perhaps there is some justice that today I should be the person most responsible for finding a peaceful solution." (Editing by Jason Webb)