COLOMBO (AFP) - Sri Lanka's former ambassador to Washington was arrested on Friday (Nov 18), accused of misappropriating more than US$350,000 (S$499,234.75), the latest member of strongman ex-president Mahinda Rajapaksa's family to be investigated for corruption in office.

Jaliya Wickramasuriya, a cousin of former president, was detained at Sri Lanka's main international airport as he tried to leave the island, an airport official said.

The police had obtained a court order preventing Wickramasuriya from leaving the country as the authorities probe financial transactions at the Sri Lankan embassy in Washington during his tenure as ambassador from 2008 and 2014.

"He is accused of pocketing US$345,000 from the purchase of a building for the embassy," a police officer involved in the investigation said.

He said two other instances of misappropriation were also under investigation, involving undisclosed sums.

The current government has accused Mr Rajapaksa and his family of siphoning off billions of dollars when they were in power and many of the close relatives are currently on bail pending court action.

Mr Rajapaksa lost power in a snap election in January 2015 to his former ally Maithripala Sirisena, who has since ordered investigations into alleged widespread graft under the former regime.

On Thursday (Nov 17), Mr Rajapaksa's younger brother Basil announced that the former president will lead a breakaway faction of the ruling coalition in an attempt to undermine Mr Sirisena, who has promised constitutional reforms and reconciliation after decades of ethnic war.