Kem Sokha (L), leader of the Cambodia National Rescue Party (CNRP), arrives before a plenary session at the National Assembly of Cambodia, in central Phnom Penh, December 7, 2016. REUTERS/Samrang Pring

PHNOM PENH (Reuters) - Cambodia’s main opposition party named Kem Sokha as its acting president on Sunday after exiled leader Sam Rainsy resigned unexpectedly in the face of a possible ban ahead of elections.

Political tension has been growing in the Southeast Asia nation, where Prime Minister Hun Sen is fighting to keep his 30-year-old grip on power and the Cambodia National Rescue Party(CNRP) could stand in his way.

An emergency meeting of the party’s committee said Kem Sokha, Rainsy’s deputy, would become the acting president.

“The CNRP knows itself, where it has come from and what it must do,” Kem Sokha wrote on Facebook. Kem Sokha had already been filling the role in effect because Rainsy lives in exile.

Rainsy announced his resignation on Saturday, saying it was to protect the party. In a video posted on his Facebook page on Sunday, he said there had been a risk that the party would be dissolved ahead of elections.

Hun Sen has said the law will be changed to ban anyone who has been convicted of an offence from leading a party.

Rainsy has been convicted of a series of defamation charges and has lived in France since 2015 to avoid them. He rejects the charges as politically motivated.

Cambodia holds local elections in June and a general election next year.