Cambodia on Friday issued an official letter to ban the opposition Cambodia National Rescue Party (CNRP) from conducting a rally on Sunday afternoon at the capital's Freedom Park.

In a letter to the CNRP, Phnom Penh Municipal Governor Pa Socheatvong said"The Ministry of Interior does not allow the Cambodia National Rescue Party to hold the people's congress at the Freedom Park or other public places in the city on March 30."

He explained that the ban on the proposed rally is due to the fact that competent authorities have not completed an investigation into cases of violent protests in January and to avoid any unrest that can arise from opportunists.

The governor said the CNRP can organize its people's congress at its headquarters or at any private locations.

The prohibition came after the CNRP's President Sam Rainsy announced Wednesday that the party would hold a people's congress at the park on Sunday afternoon with some 3,000 supporters.

CNRP said that it would defy the government ban, raising fears of violence.

Prime Minister Hun Sen warned Thursday that the government would take legal actions against any illegal protests in order to maintain peace and political stability.

"A country has its own constitution and law. If you do anything outside the law and cause violence, there will be no more tolerance, and legal measures will be taken,"he said in a public speech.

Row between Hun Sen's ruling Cambodian People's Party (CPP) and Sam Rainsy's CNRP simmered after the July election results showed that the CPP won 68 parliamentary seats against 55 seats for the CNRP.

Claiming serious ballot-rigging, the CNRP refused to accept the outcome and has boycotted parliament and conducted many protests -- some turned violent --to demand the resignation of Hun Sen and a re-election.

Hun Sen has said that he would neither step down nor call a re- vote.