Opposition candidate Tassos Papadopoulos, with strong backing from communists and other leftists, won Sunday's presidential election after a campaign in which he criticized the incumbent for giving too much away in efforts to reunify the divided island.

The election came ahead of a Feb. 28 deadline to decide on a controversial U.N. plan for the reunification of the Mediterranean island, making that decision Papadopoulos' first key task.

According to final official results, Papadopoulos won with 51.55 percent of votes cast, compared with 38.8 percent for right-wing incumbent Glafcos Clerides.

Clerides, 83, has been seeking a third term, but his defeat was widely expected and confirmed pre-election polling.

U.N. Secretary-General Kofi Annan was to visit Cyprus next week in a last ditch bid to win acceptance for the U.N. plan, and Papadopoulos said he hoped Annan would help break a deadlock in reunification talks.

"We are absolutely ready to carry out the substantive negotiations that are necessary so that we remain consistent and to prove to the international community that our commitment for a settlement remains steady and unshaken," he said in his first victory remarks.

Cyprus has been split into a Greek Cypriot-controlled south and a Turkish-occupied north since Turkey invaded in 1974 in the wake of an abortive coup by supporters of union with Greece. A breakaway Turkish Cypriot state in the north is only recognized by Turkey, which maintains 40,000 troops there.

Papadopoulos, 69, officially becomes president March 1, but Clerides has given him the green light to deal with the reunification negotiations before the Feb. 28 deadline, according to a statement released by outgoing president.

In a message to the Turkish Cypriot community, Papadopoulos said he would work "for a just and viable settlement for the benefit of both sides in a spirit of equality and within the framework of the Annan plan."

His remarks were seen as a response to intense criticism during the election campaign that he would reject the Annan plan if elected.

The president-elect also told Clerides in a telephone call that he wants the outgoing leader to help him handle negotiations as his closest adviser.

Supporters of Papadopoulos flooded Nicosia's main streets and other towns in convoys of cars with horns blaring to celebrate his victory. He was sworn in late Sunday at a Nicosia conference center.

Papadopoulos, the leader of the centrist Democratic Party, has been involved in politics for more than 40 years. At 27, he became the youngest minister to serve in a post-independence Cypriot government after the end of British colonial rule in 1959.

During the campaign, he accused Clerides of being too ready to yield on issues of principle in the reunification talks and of neglecting internal government issues.

Clerides has been leading the deadlocked U.N.-sponsored reunification talks with Turkish Cypriot leader Rauf Denktash for the past 10 years. In campaigning, he had said he was best-qualified to continue the delicate talks before Cyprus joins the European Union in 2004.

Alvaro de Soto, Annan's special envoy for Cyprus, has warned that if the plan is not accepted by a Feb. 28 deadline, "the opportunity [for a settlement] disappears until something happens, and that is totally uncertain."

If the deadline is not met, only the Greek-backed portion of Cyprus will be able to sign its EU accession agreement by April 16.

Annan's plan envisages reunification as a single state consisting of two separate Greek and Turkish Cypriot "component states" linked through a weak central government.

Greek Cypriots are deeply split over the plan.

Denktash, who is backed by Ankara, opposes the Annan proposal, because it rejects his demand for recognition of the Turkish-claimed half of Cyprus.