Hun Sen has promised to step down as prime minister while opposition figure Sam Rainsy pledges to turn himself in as forfeits if the long-term political rivals lose a “bet” over the future of former opposition leader Kem Sokha, who is on bail awaiting trial on treason charges.

Rainsy, who lives in France to avoid court action on criminal charges, wrote on his official Facebook page on Sunday: “I accept to sacrifice my freedom in order to ensure freedom for the Cambodian people”.

On Thursday, the prime minister slammed the Cambodia National Rescue Movement (CNRM) leader Rainsy’s claim last week that Sokha would be released next month. He told Rainsy to wait until “the horse grows horns” before such a development happens.

The following day, Rainsy retorted by calling on Hun Sen to “bet” with him regarding Sokha’s fate, saying the former Cambodia National Rescue Party (CNRP) leader would be released from “house arrest” between December 29 and March 3 next year.

“I believe that under international pressure, Hun Sen would be forced to release Kem Sokha soon. It could be [between] December 29, 2018, or March 3, 2019, at the latest."

“If Mr Hun Sen loses the bet with me … I am asking him to step down, but if I lose, I will walk into jail and be detained with Kem Sokha,” Rainsy said.

Responding the same day, Hun Sen told Fresh News that he accepted Rainsy’s wager and promised to step down as prime minister if he lost.

“I dare to bet with Sam Rainsy. If Kem Sokha were to be released [as Rainsy describes] I, Hun Sen, am willing to step down."

“But if Kem Sokha is not released between December 29, 2018 and March 3, 2019, Sam Rainsy must dare to surrender and immediately turn himself in for arrest,” he was quoted as saying.

Former opposition leader Sokha broke his silence on Facebook on Saturday, without mentioning either Hun Sen or Rainsy by name.

“[Sokha] is not free but he is aware [of] who [are] committing something against him and the nation,” he wrote.

Rainsy took to Facebook again on Saturday, saying he and Sokha “understand each other” because the two men are like “the same person” and share a commitment to “rescue the nation”.

“After this, we will find the truth that Kem Sokha is still keeping his same stance, united with Sam Rainsy to rescue our nation,” Rainsy said.

In a second interview with Fresh News on Saturday, Hun Sen blamed Rainsy for “pushing him into a corner” that meant he could not avoid ending Kem Sokha’s political career.

“I decided to bet with Sam Rainsy because he is the one who pushed me into a corner. I have no choice [but to accept] this bet, to kill Kem Sokha’s political life. If I did not accept [Rainsy’s] bet, [people] would say I am a coward,” Hun Sen said.

Sokha’s lawyers on Saturday issued a statement saying that any “release” of their client or having the charges against him dropped came under the authority of the court and should not be the subject of a “bet”.

They also warned that the “bet” between Hun Sen and Rainsy could “affect the procedure of the court”.

“The co-lawyers understand that using his Excellency Kem Sokha’s [situation for political gain] with [this] bet is making our nation suffer. We call on Cambodian politicians to remain moral as a good example for the next generations,” the statement said.

Political analyst Meas Nee said on Sunday that he did not believe either Hun Sen or Rainsy would go through with what they promised if their prediction proved untrue. He described their promises as political rhetoric designed to score points with the public.

And he warned that Rainsy’s strategy to use Sokha’s situation in such a way could cause internal conflict within the CNRP.

“It is a dangerous game. For Rainsy do this without asking or get acceptance from Sokha . . . I think it violates his rights and is immoral. It could cause internal conflict within the CNRP,” Nee said.