Police in the Maldives forced the postponement of Saturday's presidential polls, declaring the vote illegal and blocking ballot papers from leaving the offices of the independent Elections Commission.
The commission just hours earlier announced the vote would go ahead as planned despite 11th-hour court challenges by two candidates who were expected to lose to a former president.
"We continued with preparations for voting, but the Maldives Police Service have said no documents connected to the election can leave the commission's offices," Commission Chairman Fuwad Thowfeek said in a statement.
"A new date for elections will be informed later."
Police spokesman Abdulla Nawaz told AFP they considered it illegal to stage the election in violation of a Supreme Court order that required all candidates to approve electoral lists.
"Only one candidate had signed the voter register and therefore it would have been a violation of the Supreme Court guidelines for the election to go ahead," Nawaz said.
The Supreme Court last week annulled the first round of voting on 7 September, citing irregularities -- even though international observers said the polls were free and fair -- and ordered a re-run.
Former president Mohamed Nasheed won 45.45 percent of the vote in September -- short of the 50 percent threshold needed for outright victory.
Dozens of his supporters shouted anti-government slogans outside the national parliament in Male, but there were no reports of violence in the rain-soaked capital where residents were observing a long weekend.
Nasheed's Maldivian Democratic Party (MDP) slammed the latest scuttling of the elections and called for foreign intervention in the young democracy.
"We see a clear mandate for the international community to intervene and to restrain these undemocratic forces that are preventing a peaceful democratic political transition of the Maldives," MDP spokesman Hamid Abdul Ghafoor told AFP.
He said an "interim arrangement" should be sought through international intervention, but did not elaborate.
A US diplomat expressed concern over the latest obstacle to an election seen as vital to restore stability in the young democracy.
"The failure to hold elections this morning represents a real threat to democracy in the Maldives," said the US diplomat, asking to remain unnamed.
The election was meant to end political tensions that followed the controversial downfall of Nasheed in February last year, but it has caused more instability in a country that embraced multi-party democracy in 2008.
Forty-six-year-old Nasheed says he was ousted in a coup involving rogue elements in the police last year.
Nasheed, the frontrunner for the latest polls, insisted Friday that the election go ahead as planned, dismissing the challenge by business tycoon Qasim Ibrahim, who came third in last month's aborted poll, and Abdullah Yameen, who was a distant second.
The police announcement meant the Elections Commission could not transport some ballot boxes to remote islands in the archipelago of 1,192 coral islands scattered 850 kilometres (530 miles) across the equator.
The election was to be held in the 202 inhabited islands as well as some of the tourist resort islands where Maldivians are employed in the country's most important income generator.
Yameen, the half brother of the islands' long-time ex-ruler Maumoon Abdul Gayoom, won 25.35 percent of the votes in September's poll and would have faced Nasheed in a run-off but the decision to order a re-run allowed third-placed candidate Ibrahim to reenter the contest.
Gayoom ruled the Maldives for 30 years until he lost the first democratic election in 2008 to Nasheed. But observers say Gayoom's supporters still control key levers of power such as the judiciary and do not want to see Nasheed return to office.
Outgoing president Mohamed Waheed, who replaced Nasheed but is not running again, had promised a smooth transition of power. He was humiliated in the 7 September vote, winning just over five percent of ballots.