Prime Minister Hun Sen on Saturday hit back at a proposal from a former deputy prime minister that ousted prime ministers be given legal immunity and be recognised as “national heroes”, labelling the proposal a “trick” from the opposition party.

Hun Sen, who is now in his 33rd year of office, said in a statement published by the government-aligned Fresh News on Sunday that the proposal from Lu Laysreng, a Funcinpec deputy prime minister from the coalition in the 2000s, was “a dirty request”.

“Lu Laysreng, don’t come out and be an elder and a veteran politician. Who has appointed you as an elder?” Hun Sen said, going on to further slam his former deputy’s political pedigree by pointing to the royalists’ collapse since they won the 1993 election.

“You were a member of Funcinpec from when it had seats in the National Assembly to when they’re all gone. Don’t make yourself a politician any longer. You’re under my control, and I know clearly about the relations between you and the opposition,” he said.

Hun Sen said he had no doubts about Laysreng’s ill intentions in making such a proposal.

“It’s to show that the CPP is preparing to lose, and the opposition is preparing for victory. It’s like a crocodile and a tiger preparing to feed, while it’s their party that has truly lost to the CPP,” he said.

Laysreng had earlier in the day penned letters to Hun Sen and opposition leader Kem Sokha asking them to legislate that all premiers receive legal immunity upon leaving office – seemingly to mitigate any concerns that Hun Sen may have about reprisals if he loses power.

“I remember, and never forget, that our country achieving peace thus far has been the achievement of Samdech Techo Hun Sen, and there is no one who can argue with that,” Laysreng wrote in his letters, also appealing to the two leaders to support the law.

“To keep peace for a stable nation, I would like to request that Samdech Techo, as CPP president, request that the National Assembly make a law to protect all prime ministers whose mandates expire, giving them immunity and promoting their titles as ‘national heroes’,” he wrote. “This law, I believe all Khmer citizens would welcome and support.”

Pol Ham, a deputy president of the opposition Cambodia National Rescue Party, declined to comment on the case. However, Laysreng, who regularly appears at CNRP events, denied he had ill intentions and said he was trying to facilitate both sides talking.

“It was not my intention to look down [on anyone]. I already said that for the next mandate’s election, I do not know who wins,” Laysreng said, insisting his proposal was not specifically intended to refer to Hun Sen. “This remark was in general – for all.”

Ou Virak, a political analyst who heads the Future Forum think tank, said he thought creating such a law would incentivise bad behaviour, and that he believed more substantive efforts were needed to build trust between the parties ahead of next year’s election.

“It’s not possible. If we did, the prime minister could do whatever he wants,” Virak said. “To solve the problems we have at present, [we have to] demand our politicians have some flexibility, and give each other the confidence to take steps toward national unity.”

Thoughts of the end of his rule appear to have been at the front of Hun Sen’s mind in recent days. Last week, the premier lashed out at a social media user who said he was abroad receiving medical treatment but had failed to appoint anyone as acting premier, as is customary, due to a lack of trust in other CPP leaders.

Hun Sen at the time posted photos to his Facebook page appearing to show him in Singapore eating in a restaurant and visiting a mall with his family. In a response to the rumours, he insisted that he was able to run the country wherever he was, particularly when it came to “cracking down on ... national traitors”.

In some of the photos, however, he appeared to be wearing a back brace.

In an apparent bid to dispel any lingering questions over his health, Hun Sen posted videos over Saturday and Sunday of himself travelling around Phnom Penh in a van, as well as driving cars and meeting citizens.

“There was some contact on WhatsApp and Telegram and claims from person to person that I was seriously sick and that [my relatives] understood I was being sent to France, and some more said I was being sent from Singapore to Hong Kong,” Hun Sen said in one clip.

“But now I am in front of the Phnom Penh Hotel, meaning that I am riding around looking at Phnom Penh. The bad rumours should be eliminated through my video clip”, he said. “I am travelling normally, and getting stuck in traffic jams like other people.”

“If the prime minister lost his title like what they have raised, it is clear that this country would be turbulent, but I ask compatriots to be confident in my responsibility,” he added.