Police in the Maldives forced the postponement of Saturday's presidential polls, declaring the vote illegal in a decision that sparked international concern.
The Elections Commission just hours earlier had 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, adding a new election date would be announced later.
Regional power India issued a strongly worded statement expressing deep disappointment over the cancellation of an election that had international support.
"India and the international community have been closely watching the developments in Maldives and are seriously concerned at the attempts to stall the democratic process," the Indian foreign ministry said in a statement.
New Delhi demanded that Maldivian authorities make sure a fresh election is held without delay to ensure a president is in office by the constitutionally mandated November 11 deadline.
Police spokesman Abdulla Nawaz told AFP they considered it illegal to stage the election in violation of a Supreme Court order requiring 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 court last week annulled the first round of voting on September 7, citing irregularities -- even though international observers said the polls were 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 parliament in Male and some sat on a sidewalk holding a banner asking: "Where is our vote?"
But there were no reports of violence in the rain-soaked capital where it was a long holiday 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," 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.
"The failure to hold elections this morning represents a real threat to democracy in the Maldives," said the 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. The 46-year-old says he was ousted in a coup involving rogue police elements.
Nasheed, the frontrunner for the latest polls, insisted Friday 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 across the equator.
The election was to be held in the 202 inhabited islands as well as some tourist resort islands where Maldivians are employed in the country's biggest income generator.
Yameen, 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 rejoin 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 power levers 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 September 7 vote, winning just over five percent of ballots.