Maldives President Abdulla Yameen declared a state of emergency on Wednesday, giving sweeping powers to security forces to arrest suspects ahead of a major anti-government protest rally, his spokesman said.

The move came two days ahead of a planned protest by the main opposition Maldivian Democratic Party (MDP), whose leader Mohamed Nasheed is in jail after a widely criticised conviction under anti-terror laws.

"President Yameen has declared (a) state of emergency to ensure the safety and security of every citizen," his spokesman Muaz Ali tweeted.

The MDP rally in the capital Male is aimed at pressuring Yameen to release Nasheed, whose incarceration has been severely criticised by the UN and international rights groups.

The move comes at a time of heightened tensions in the honeymoon island nation following an explosion aboard President Yameen's speed boat on September 28 that wounded his wife and two others.

Yameen was unharmed in the blast, and the US Federal Bureau of Investigation has said there is no evidence it was caused by a bomb.

But the authorities say it was an attempt on his life and Yameen arrested his deputy Ahmed Adeeb on October 24 after accusing him of "high treason" and linking him to the boat blast.

Then this week the Maldivian National Defence Force (MNDF) said it had found a remote-controlled bomb near the president's official residence and safely defused it.

Over a third of the country's 340,000 Sunni Muslim population lives on the capital island Male, where authorities said the device was found.

Official sources said the declaration of a state of emergency meant several provisions of the constitution would be suspended.

This would prevent lawmakers from impeaching the president and make it easier for authorities to detain people, they said.