The incident occurred on Monday as President Abdulla Yameen and several others were being taken from an airport to the shore. Yameen, who was returning from the hajj pilgrimage in Saudi Arabia, was unhurt, but his wife and two aides were injured.

The cause of the blast was unclear. Maldives authorities have requested the aid of the US Federal Bureau of Investigation and the Australian federal police for help in investigating, although authorities have played down the possibility of an assassination attempt.

"We are looking at an accident rather than sabotage," said Mohamed Hussain Shareef, minister at the President's Office.

"But until they find it fully, nothing can be ruled out," he added.

Maldives, a popular tourist destination, was a center of controversy after Yameen came to power in a hotly contested presidential election in 2013. His rival, then-President Mohamed Nasheed, was given a 13-year jail sentence earlier this year under charges of terrorism, drawing criticism from around the globe. Nasheed's attorney, the human rights lawyer Amal Clooney, has threatened to press for sanctions if he is not released.

The country has also seen a broader crackdown on freedom of speech, with various dissidents jailed for speaking out against the current president. In May, US Secretary of State John Kerry expressed concern over the arrests.

blc/kms (AFP, Reuters, dpa)