Prime Minister Hun Sen took aim at former opposition leader Sam Rainsy in a speech today, mockingly characterising his long-time rival as loser – and an old one at that.

“The one who wants to replace me as prime minister is older than me. They should take somebody younger to replace the older,” the premier said to a crowd of garment workers in Phnom Penh's Por Sen Chey district.

Rainsy, at 68, is three years older than Hun Sen, though the latter has been in power for 33 years, and has pledged to serve another 10 as prime minister.

Hun Sen also poked at his rival’s lack of electoral success, leaving out the fact that many observers have questioned the integrity of Cambodian elections, including the coming National Assembly election scheduled for July.

Rainsy is currently in self-imposed exile avoiding a host of politically tinged convictions, and the party he helped to found – the Cambodia National Rescue Party – was forcibly dissolved at the government's behest in November. The decision also banned 118 of its senior members from participating in politics for five years.

“He said I am afraid of him, that’s why I didn’t allow him to join the election," Hun Sen said of Rainsy. "If you are a convict how can you join the election?”

Indeed, Cambodian law forbids political parties from so much as using the image or writings of "convicts" for the party's benefit, let alone accepting convicted criminals' help. That highly contentious amendment to the Political Parties Law was rammed through parliament by Hun Sen's Cambodian People's Party last year in the run-up to the CNRP's dissolution. It and a companion set of amendments forbidding convicted criminals from holding leadership positions in parties were both seen as being targeted directly at the CNRP, and specifically Rainsy.

Not long after the amendments forced Rainsy out of politics, his successor, Kem Sokha, was arrested on widely decried charges of "treason'. Another provision included in the same amendments – this one forbidding parties from conspiring with foreign powers – formed the government's justification for dissolving the CNRP some two months later.

Hun Sen, however, suggested something else had kept Rainsy from succeeding all these year. Rainsy, Hun Sen said in a final taunt, “never wins” elections because he “wants to be Prime Minister too much”.

Responding to the barbs, Rainsy today agreed with Hun Sen that space should be made for younger leaders, taking the idea a step further and proposing to create a law requiring that Cambodia's prime minister be under the age of 65.

“It would be a concrete, more than symbolic gesture to show that we both really want to promote the new generation,” he said in an email.

But the election-related taunts Rainsy characterised as “silly language” that revealed to the world that Hun Sen is “a coward”.

Political analyst Meas Nee, meanwhile, condemned both Hun Sen and Rainsy for reverting to “personal attacks”, but allowed there could be an element of fear motivating Hun Sen's attacks on the former opposition.

“If he was not afraid of Sam Rainsy, maybe he would just keep quiet instead of reacting to everything he says,” he said.