LEADER of the opposition Cambodia National Rescue Party Sam Rainsy has resigned from the party effective today, according to a statement.

The long-time opposition leader released statements on his Facebook and Twitter accounts, the latter saying his decision was "for the sake of the party".

It reads: "I resign as CNRP leader for the sake of the party. In all circumstances cherish and uphold the CNRP's ideals in my heart."

In a statement on his Facebook account, Rainsy said:

"I Sam Rainsy, the president of the Cambodia National Rescue Party, would like to inform the permanent committee and steering committee of the Cambodia National Rescue Party of my resignation as a president and member of the Cambodia National Rescue Party due to my own reasons.

"As aforementioned, I would like that the permanent and steering committees of the Cambodia National Rescue Party be informed of my decision and regard this decision as in effect from the day of signing."

The letter is signed February 11.

The resignation soon comes after Prime Minister Hun Sen recently threatened to change laws governing political parties to enable the government to dissolve parties whose members have committed criminal offences.

The premier also called for changes to the same law to prevent people with criminal convictions from leading political parties.

A vote on the amendments is scheduled for April 1, a ruling Cambodian People's Party lawmaker said last week.

Rainsy, a former Minister of Finance with the royalist party Funcinpec, has led the CNRP since it formed in 2012 as merger between his own Sam Rainsy Party and Kem Sokha's Human Rights Party.

Rainsy has not stepped foot in Cambodia since late 2015, when he chose not to return and face a two-year prison sentence revived while he was abroad in South Korea.

Sokha, who has been acting president of the party during Rainsy's absence, is expected to take charge of the party, as it prepares for upcoming commune elections in June.

Opposition spokesmen were not immediately reachable, and a request for comment to Rainsy was not returned as of press time. CNRP lawmaker Mu Sochua said she had not yet been made aware of Rainsy's decision.