The European Commission praised the Turkish Cypriot 'yes' vote
Cyprus has missed an historic opportunity to resolve 30 years of division, UN Secretary General Kofi Annan has said.
Mr Annan was reacting to the Greek Cypriots' overwhelming rejection of a UN plan to reunite the island; Turkish Cypriots voted in favour of the move.
The island will remain "divided and militarised" as it joins the European Union on 1 May, Mr Annan said.
The EU has signalled that it will seek ways to end the economic isolation of the Turkish Cypriot state.
Both sides had to approve the proposals for Cyprus to be reunified in time for EU membership. The result means that EU laws and benefits will apply only to the Greek Cypriot community.
Over three-quarters of Greek Cypriots voted "no" in Saturday's referendum, unhappy at limits on their right to return to property in the Turkish North.
Turkish Cypriots, in contrast, endorsed the plan with a 65% majority, seeing it as a way to end the international isolation they have endured since Turkish troops invaded the island in 1974.
"A unique opportunity to bring about a solution to the long-lasting Cyprus issue has been missed," the European Commission said in a statement.
The EU's commissioner for expansion, Guenter Verheugen, was more blunt.
"There is a shadow now over the accession of Cyprus," he told Germany's ARD television.
"What we will seriously consider now is finding a way to end the economic isolation of the Turkish Cypriots."
Alvaro de Soto, the UN envoy who worked on the failed peace plan for nearly five years, said his office would close in the coming weeks.
Asked how he felt, he told the Associated Press, "I would have to bite my tongue."
The US said it was "disappointed" with the result, which was a "setback to the hopes of those on the island who voted for the settlement and to the international community".
The Greek Cypriot rejection came as no surprise, but the margin was far larger than expected.
Diplomats had hoped the deal would be defeated only narrowly, and that the same plan might be put to the people once again in a few months' time.
But the nature of the result appears to rule this possibility out, says the BBC's Tabitha Morgan in Nicosia.
Greek Cypriot President Tassos Papadopoulos, who urged voters to reject the plan, said he remained committed to reaching a deal with the north.
"Today's result must act as a catalyst for reunification, and not be used as an excuse for further division," he said.
But hardline Turkish Cypriot leader, Rauf Denktash - a fierce opponent of the UN plan - called on the world to stop pressing the two sides to live together.
"There must be no uncertainty caused by futile attempts to force incompatible parties together," Mr Denktash said.
His Prime Minister Mehmet Ali Talat - a supporter of the plan - called on the UN and the EU to take measures to redress the irony that the side that rejected the plan will become an EU member in a week's time.
Mr Talat said the isolation of northern Cyprus must be ended or alleviated - a call echoed by Turkey.
"The embargoes must be lifted, the isolation must be brought to an end," said Turkish Foreign Minister Abdullah Gul.
After this vote, he said, Ankara would not pull its 30,000 troops out of Cyprus.
The plan crafted by UN Secretary-General Kofi Annan envisaged a loose federal structure for the island.
Many Greek Cypriots refugees who fled the Turkish assault would have been allowed to return and recover some of the land they lost.
But the Greek side was unhappy that the plan limited their right to return, while allowing tens of thousands of Turkish settlers introduced since 1974 to remain.