PHNOM PENH (AFP) - A Cambodian court on Monday (June 13) sentenced three more opposition activists to seven years each in prison over their alleged roles in post election protests that turned violent two years ago.

The jailings come as political tensions in Cambodia soar with the opposition party embroiled in a sex scandal and strongman Prime Minister Hun Sen accused of carrying out a fresh crackdown against critics.

Three youth members of the Cambodian National Rescue Party (CNRP) were found guilty of insurrection by the Phnom Penh Municipal court on Monday.

The three men were arrested last year after another 11 opposition officials and activists were jailed on the same charges - including three who received 20-year sentences.

The convictions, condemned as politically motivated by rights groups, stem from clashes between protesters and authorities in July 2014 during a demonstration against the closure of Freedom Park, a key site for public rallies in Phnom Penh.

Dozens of security officers and several protesters were injured in the clashes.

At the time the park was a rallying point for Hun Sen's opponents who accused him of rigging the previous year's elections.

The CNRP are currently involved in a fresh standoff with the authorities.

Secret phone calls allegedly between the party's deputy leader Kem Sokha and a mistress were released earlier this year.

He is now wanted for questioning by a court after a prostitution investigation was launched against the woman. But he has refused to be interviewed, arguing that the police investigation is politically motivated, and has holed himself up in the CNRP's headquarter since late May after armed police tried to arrest him.

Hun Sen's government has denied targeting Kem Sokha but has gone on to arrest dozens of critics in recent weeks.

Among them are human rights defenders, environmental campaigners, monks, students, opposition party activists and politicians.

Am Sam Ath, of local rights group Licadho, said Monday's jailing would fuel further political resentment.

"The political situation is tense now, and the sentences will add to the heat," he told AFP.

In a speech on Monday morning, Hun Sen vowed to crack down on any demonstrations.

"I tell you first that I won't tolerate them. Authorities must keep security and social order," he said.

Hun Sen has ruled Cambodia with an iron fist for more than three decades.

But the opposition's popularity has grown amid growing disillusionment with the endemic corruption, rights abuses and political repression under his watch.

The premier's main rival, opposition leader Sam Rainsy, has been forced to live in self-imposed exile abroad to avoid arrest warrants that he says are politically motivated.