MALE, Maldives (AFP) - Ballot counting began late Saturday in elections in the Maldives to choose a new president and avert a constitutional crisis after two previous attempts to select a leader were scuttled.

Opposition leader Mohamed Nasheed, ousted as president nearly two years ago in what he called a coup, is seeking to return to power and hoping for a first-round victory. The independent Elections Commission began counting ballots after the polls closed and said it expected initial results by early Sunday.

"Polling proceeded smoothly and peacefully across the country," the foreign ministry said in a statement.

The election was observed by over 2,000 local and foreign monitors across the archipelago of 1,192 tiny coral islands.

However, a run-off planned for Sunday in the event no candidate wins more than 50 per cent of the vote may be in doubt, Chief Elections Commissioner chief Fuwad Thowfeek told reporters in the capital Male.

The two other candidates, Abdulla Yameen and Qasim Ibrahim, were yet to approve voter lists, a requirement by the Supreme Court for a run-off to take place, he said, threatening a constitutional crisis.

Under the constitution, a new president must be sworn in by Monday in the Sunni Muslim nation of 350,000.

The Maldives, whose turquoise seas and white beaches have long been a tourist draw, has been the focus of intense US-led diplomatic pressure since judges annulled results of a September 7 vote.

When new polls were scuppered six weeks later, suspicions grew that authorities were determined to prevent Mr Nasheed from returning to power at any price.

The 46-year-old - a one-time political prisoner and environmental activist - won the first multi-party elections in 2008, ending 30 years of iron-fisted rule by Maumoon Abdul Gayoom. But after clashing with key institutions, including the judiciary and security forces, he was forced to resign in February 2012.

Mr Nasheed is expected to emerge victorious, having secured a clear lead over his two challengers in the September 7 vote, even though he fell just short of the absolute majority needed to win in the first round.

The Supreme Court annulled the September results, saying voter lists were flawed even though international observers gave the outcome the all-clear.

On Saturday, the MDP said there were no issues with voter lists except for spelling mistakes that authorities corrected.

Mr Nasheed's two challengers - Mr Gayoom's half brother Mr Yameen and business tycoon Mr Ibrahim - thwarted the rescheduled vote October 19 by refusing to endorse an updated electoral roll. There was no comment from either.