COLOMBO (AFP) - The Maldives presidential election on Sunday (Sept 23) will not be free and fair because President Abdulla Yameen has used draconian laws to crack down on rivals, a foreign monitoring group said on the eve of voting.

The Asian Network for Free Elections (ANFREL) said the political environment in the tourist paradise was heavily tipped in favour of Mr Yameen and they did not expect a fair contest.

"The ANFREL denounces recent developments... which ensure that the upcoming presidential election of Sept 23 cannot be considered free and fair," the group said in a statement.

It said it was recognised by the Maldives Election Commission and given accreditation to monitor the voting, but that its staff were denied visas to enter the country.

A number of international journalists have also been denied permission to cover the polls.

"It appears that Maldivian authorities are granting visas only to observers and monitors they perceive as friendly, while using ANFREL's name and that of other applicants in an attempt to gain international legitimacy," the organisation said.

The statement came a day after exiled former leader Mohamed Nasheed urged the international community not to accept the outcome of what he said would be a flawed ballot.

Mr Nasheed, the country's first democratically-elected leader, told reporters in neighbouring Sri Lanka that Mr Yameen would "lose the election" but would "hold on to power" after rigging the electoral process.

ANFREL also asked foreign governments to be vigilant about the election and predicted "sombre events" for the 340,000 Maldivians in a country otherwise known as a paradise for well-heeled tourists.

Mr Nasheed was forced to withdraw from the contest after the Maldives Election Commission disqualified him because of a 2015 terrorism conviction.

The United Nations has said Mr Nasheed's conviction and 13-year jail term were politically motivated and asked Mr Yameen's government to overturn the decision and pay him reparations.

Mr Nasheed has lived abroad since travelling out of the country on prison leave. His Maldivian Democratic Party (MDP) is the main challenger in Sunday's vote after securing the support of all other opposition parties.

A relatively unknown politician, Mr Ibrahim Mohamed Solih, 54, is backed by Mr Nasheed to try to beat Mr Yameen, who came to power following a controversial run-off against Mr Nasheed in the 2013 election. The second round of voting was delayed, giving Mr Yameen more time to pull together a coalition.

The United States and European Union have expressed deep concern over Mr Yameen's actions, and rights activists have called for sanctions on the President and his aides.