Hun Sen a 'coward' says Cambodia opposition chief

Rainsy, Hun Sen's main rival, lives in self-imposed exile in France to avoid prison for a string of convictions that critics contend are politically motivated.

In November the 63-year-old Rainsy was told he could not stand in the polls because of his convictions by the National Election Committee (NEC), a body he says is a tool of the premier.

He accused Hun Sen, who has ruled the country since 1985 and has vowed to stay in power until he is 90, of using the NEC to block his election bid -- something the premier has repeatedly denied.

"I think Hun Sen is a coward because there are only two challengers," he told AFP by telephone from Yangon, where he met Myanmar's pro-democracy leader Aung San Suu Kyi.

"But Hun Sen dares not to compete with me. He uses a kangaroo court to blame me so that he can go into the ring and fight alone."

Hun Sen, 61, is routinely accused of suppressing political freedoms and violating the rights of dissidents, but analysts say he remains firmly entrenched in power.

Rainsy, who leads the recently-formed Cambodia National Rescue Party, said he still harboured hopes of running in July's election and expressed confidence his party could end Hun Sen's 28-year grip on power.

Suggesting Hun Sen is committing "political suicide" by not allowing him to compete, Rainsy warned he will "start a strong movement to topple" any government formed by the election.

He also accused the NEC of handing Hun Sen's ruling Cambodian People's Party (CPP) landslide victories in successive elections.

French-educated Sam Rainsy is one of the most outspoken figures in Cambodian politics but has lived in self-imposed exile in France since 2009, and faces a total of 11 years in prison if he returns.

In 2010 he received a seven-year jail term in absentia for publishing a 'false map' of the border with Vietnam, claiming the neighbour holds Cambodian territory.

Other convictions include accusing the foreign minister of being a member of the brutal Khmer Rouge regime in the late 1970s.

The international community has urged Cambodia to allow all political participants, including Rainsy, to compete fairly in the looming election.

Despite his apparently unassailable grip on power, some experts question whether Hun Sen's strong-arm tactics could eventually bring him down.

"How can he rule by fear and at the same time try to keep everybody happy?" Ou Virak of the Cambodia Center for Human Rights recently told AFP.