COLOMBO (AFP) - The Maldives parliament has sacked the country's vice-president and accused him of treason, as international concern mounts over the state of democracy on the honeymoon islands.

Lawmakers voted overwhelmingly on Tuesday evening to oust Mohamed Jameel, who was the running mate of President Abdulla Yameen in a controversial 2013 election but has now fallen out with him.

The 45-year-old, who was abroad at the time of the vote, was also accused of colluding with the opposition, although the precise nature of the charge remains unclear.

Yameen's defence minister has also been jailed on charges of trying to topple the government.

Yameen already faces international criticism for the jailing of the country's main opposition leader and former president Mohamed Nasheed for 13 years on charges of terrorism.

The United Nations said the trial of Nasheed, the country's first democratically elected leader, was "vastly unfair", while US Secretary of State John Kerry warned that democracy was under threat.

Jameel had fallen out with Yameen, the half-brother of former Maldivian strongman Maumoon Abdul Gayoom who ruled for three decades till 2008.

The former vice-president, who was not allowed to defend himself in parliament, accused Yameen of undermining the rule of law.

"This is a testament to the state of the rule of law in the Maldives," he said in a statement quoted by the local Minivan News service.

"Every act was planned at driving a wedge between myself and the people who elected me. My reputation was threatened and finally I started receiving threats to my life."

The image of the Maldives as an upmarket tourist destination has been dented by political unrest since the toppling of Nasheed in February 2012.

Yameen came to power in 2013 after a run-off vote that had been delayed on the orders of the supreme court following a first-round election led by Nasheed.

Jameel is tipped to be replaced by tourism minister Ahmed Adeeb, a strong supporter of the president.