COLOMBO (AFP) - A Sri Lankan court on Monday (Aug 15) remanded in custody the eldest son of Sri Lanka's strongman former president on a fresh money-laundering charge.

Namal Rajapakse, who is a legislator from an opposition faction loyal to his father Mahinda Rajapakse, was remanded in custody for a week in a hearing at a magistrates' court in the capital Colombo.

"The order was given in connection with a new allegation that he was responsible for laundering 45 million rupees (S$416,208) through two of his companies," a court official told the AFP.

It is the second such accusation to be filed against Namal, who is also facing separate charges that he accepted more than US$500,000 (S$671,945) from an Indian company as a kickback to speed up a property development venture in Colombo.

The ex-president's younger son Yoshitha is already facing similar money-laundering charges over dealings at his private television channel, Carlton Sports Network.

In April last year authorities arrested Mahinda Rajapakse's younger brother Basil, who was a government minister under his sibling.

The ex-president and his relatives controlled nearly 70 per cent of Sri Lanka's national budget during his rule that ended in January 2015, when he was defeated at the polls by his former ally Maithripala Sirisena.

The new president has vowed to investigate allegations that members of Rajapakse's family siphoned off billions of dollars from the country during his nearly 10-year rule.