NEW DELHI (AFP) - The President of the Maldives has left the country on the eve of national elections that have been delayed three times, his spokesman said on Friday, leaving a leadership void amid a constitutional crisis.

Mr Mohamed Waheed, who took office after a contested transfer of power last February, left for Hong Kong and Singapore on Thursday evening to accompany his wife to a medical appointment, spokesman Masood Imad said.

Presidential elections are to be held on Saturday.

"I believe it was an appointment they had for some time that they deemed not necessary to postpone any more," Mr Imad told AFP, saying Mr Waheed's wife was suffering from an eye problem.

Mr Waheed, who as President commands the country's armed forces, would not be back for a month, he added.

Pressure has been mounting on the former United Nations official from Western nations and India, with the European Union warning of "appropriate measures" this week if the Indian Ocean islands failed to hold a free vote.

Under the terms of the constitution, Mr Waheed's term in office officially lapsed last weekend, but he said he would remain in power to allow the selection of a replacement.

The tourism-dependent country has been gripped by protests and instability since February last year when the country's first democratically elected president Mohamed Nasheed resigned.

He said he was forced out four years into his term by mutinous security officers acting on the orders of former autocrat Maumoon Abdul Gayoom and Mr Waheed, then his vice-president.

Both accused men denied the allegations.

A first round of presidential elections was held on Sept 7, which were won with 45 per cent of the vote by Mr Nasheed, a pro-democracy campaigner regularly imprisoned during the 30-year rule of Mr Gayoom.

He faced a second-round run-off vote against the former leader's half-brother Abdulla Yameen, which was scuttled by the Supreme Court, which unheld a complaint about vote list irregularities.

Two further scheduled elections announced by the Election Commission were prevented.

Mr Nasheed, who has promised to bring the perpetrators of the "coup" against him to justice if elected, will face Mr Yameen in Saturday's run-off vote.