The Federal Bureau of Investigation (FBI) has found "no conclusive evidence" of a bomb blast on the boat of Maldivian President, the US said on Sunday as it cautioned the island’s government on the state of emergency and provisions in the newly-enacted anti-terrorism law that could be used to target opponents.

Disputing the findings of the Maldivian government on explosives, the US State Department spokesman said there was no conclusive evidence that the blast was caused by an improvised explosive device (IED).

"Based on the FBI’s analysis – which included forensic analysis of the scene, analysis of the items recovered from the scene, and chemical testing – there is no conclusive evidence to attribute the explosion on the boat to an IED," the spokesman said.

"The submitted specimens were determined to be components from the boat and not the components of an IED," he said.

President Abdulla Yameen was unharmed in the explosion on his official boat on September 28 that slightly injured his wife and led to the arrest of his deputy – Vice President Ahmed Adeeb.

On November 4, President Yameen declared a state of emergency for 30 days citing threat to national security and gave sweeping powers to security forces while suspending right to freedom of movement and assembly after arms and explosives were found near his palace.

The US also cautioned Maldives about the provisions in the new anti-terrorism law passed last week which can be used to target political opponents.

"We are concerned that provisions in the anti-terrorism law passed in Maldives last week and the subsequent state of emergency could restrict human rights and fundamental freedoms," the state department spokesman said.

"The freedoms of expression, association, and peaceful assembly must be protected in the fight against terrorism and we are concerned these measures could be used to target critics of the government," the spokesman said.

As such, the US exhorted Maldives to prevent abuse and ensure that civil and political rights are respected.

The US also expressed its concern over reports of continued politically-motivated arrests and call on Maldives to afford all its citizens due process of law.

Responding to a question on the status of former President Mohammed Nasheed, the spokesman said the US is disturbed by his ongoing imprisonment.