The Maldives Supreme Court Monday annulled the results of last month's presidential elections, in a move likely to deepen international concern amid high tensions on the troubled Indian Ocean archipelago.

The court annulled the first round of voting, which was held on September 7 and won by former leader Mohamed Nasheed, and ordered a fresh ballot.

The Maldivian opposition appealed to foreign holidaymakers Saturday to boycott the upmarket tourist destination as authorities indefinitely postponed a presidential runoff amid mounting international concern.

The runoff had been slated for Saturday between human rights activist Mohamed Nasheed and Abdulla Yameen, a half-brother of former president Maumoon Abdul Gayoom, who ruled the Maldives with an iron fist for three decades before the first elections in 2008.

The Maldives' Election Commission sparked confusion on Friday over whether elections originally scheduled for this weekend but suspended by the Supreme Court would go ahead on the troubled Indian Ocean archipelago.

The chief of the independent election body Fuad Thaufeeq told local media late Thursday that voting would take place in defiance of the Supreme Court order, which has been criticized by the international community.

International pressure mounted on the Maldives on Wednesday to go ahead with a presidential run-off election due this weekend which the Supreme Court has suspended.

Canada, Australia and the European Union joined the Commonwealth, the United States and other countries in calling on authorities to hold the vote on Saturday as previously scheduled.

The Supreme Court of the Maldives on Monday delayed the final round of presidential elections due this weekend following a legal challenge, threatening more political instability in the troubled Indian Ocean archipelago.

"We order the Elections Commission and other relevant state institutions to delay the second round of the presidential election scheduled for 28 September 2013 until the Supreme Court issues a verdict in this case," read a ruling from the court.

The ex-leader of the Maldives, Mohamed Nasheed, faces a tricky run-off after failing to win a majority in presidential polls he hoped would seal his return to power 18 months after he was toppled.

Nasheed was the clear winner of Saturday's first round but analysts said he would be disappointed in failing to pass the 50 percent threshold and would now face an uphill task to seal his comeback in the second round of voting on September 28.

The president of the Maldives on Friday promised a free and fair election this weekend 18 months after a violent change of leadership shook the Indian Ocean archipelago.

"The atmosphere is ready for free and fair elections," Mohamed Waheed told Agence France Presse as the candidates standing in the presidential poll wrapped up campaigning in the popular holiday destination.

Police in the Maldives detained opposition leader Mohamed Nasheed on Tuesday, defying pressure from regional power India which had called for him to be free to campaign for elections.

Twenty masked policemen in riot gear arrested Nasheed at his family home in the capital Male and one of his security men was hurt in the melee, Shauna Aminath, a spokeswoman for Nasheed's Maldivian Democratic Party, said.

The United States and the United Nations called Thursday for free elections in the Maldives, after the Indian Ocean archipelago's former leader took refuge in the Indian embassy.

"We urge all sides to remain calm, reject the use of violence and avoid rhetoric that could increase tensions," State Department spokeswoman Victoria Nuland said in a statement.

The Maldives is to hold presidential polls on September 7, the first since the archipelago's first democratically elected leader was toppled in what he called a coup, the government said Wednesday.

On the eve of the anniversary of president Mohammed Nasheed's ouster on the honeymoon islands, a top aide to his successor as president said arrangements had already begun to prepare for the election.