Two days before a NATO summit, Greece Monday again warned its northern neighbour it will veto an invitation to Macedonia to join the Western alliance unless a solution is found to the long- running name dispute, according to dpa. Greece is in negotiations with the Former Yugoslav Republic of Macedonia (FYROM) to end the dispute before the April 2 summit in Romania, when Croatia, Albania and Macedonia are to be considered for membership. Greece has been in dispute with the Former Yugoslav Republic of Macedonia - to use its official title - over the issue of the latter's name ever since it broke away from Yugoslavia in 1991. NATO member Greece has threatened to veto the invitation if FYROM does not change its constitutional name on the grounds that it could imply claims on the northern Greek province of the same name, and could destabilise the region. "Greece's foreign policy (is seeking) to have ties with FYROM smoothed over on the basis of a mutually acceptable solution," said Greek Foreign Minister Dora Bakoyianni. "No mutually acceptable solution means no NATO invitation," she added. United Nations mediator Matthew Nimetz has proposed the "Republic of Macedonia (Skopje)". Skopje last week said it would let the national assembly vote on the proposed UN name for the first time in the 17-year dispute. But with no sign that Greece would approve the compromise, Skopje decided to cancel a parliamentary debate on changing the country's name. Greece's stance has aroused consternation in both the United States, the European Union and NATO, where some member states fear that a rejection of Skopje could jeopardize stability in the Balkans. The dispute has resulted in growing tension in both countries. Athens Monday protested over several billboard ads hoisted on the streets around Skopje on Monday, which replaced the blue cross on the Greek flag with a Swastika.