The Cambodian parliament has ratified a controversial border agreement with Vietnam, following a government campaign to suppress dissent over the issue.

All 97 lawmakers present at the National Assembly Friday voted to approve the contentious accord. However, 14 opposition party lawmakers earlier walked out of the chamber, to protest the treaty and the limited time they were given to ask questions.

The three-part agreement is a supplement to a 1985 border treaty, and is seen to legitimize that earlier document.

Border expert Sean Pengse, one of the treaty's critics, says Cambodia may not have entered the 1985 agreement voluntarily, since the treaty was signed while the country was under occupation by Vietnam. He says the treaty gives away land and maritime areas that have historically belonged to Cambodia.

Vietnam occupied the country after the fall of the genocidal Khmer Rouge in 1979, and installed many of the leaders of the current government. Relations with Vietnam remain a sore point for many Cambodians.

Prime Minister Hun Sen and his deputy, Sok An, took up most of Friday morning speaking in favor of the treaty. Coalition lawmakers accused the opposition, including Sean Pengse, of opposing the treaty for their own political advantage.

Following the vote, the prime minister called the passing of the treaty a historic mission to pave the way for peaceful and friendly relations with Vietnam.

The prime minister said Cambodia will work to implement the treaty to demarcate the Cambodian-Vietnam border, and will continue negotiations on disputed land and maritime boundaries.

Mr. Hun Sen returned from signing the treaty in Hanoi last month vowing to sue anyone who accused him of giving away Cambodian land. His government promptly ordered the arrest of a popular independent journalist for broadcasting an interview critical of the treaty.

A teacher's union president was also jailed, for signing a press release blasting the government's border policy. The two men are being held on criminal defamation charges.

Four other people wanted for arrest for allegedly defaming the prime minister have fled the country. Human rights leaders and journalists, including a reporter for the Voice of America Khmer service, have also left Cambodia to avoid arrest.

Prior to Friday's vote, the prime minister launched a campaign on national television and radio in support of the treaty. He also threatened to dissolve the monarchy if King Norodom Sihamoni did not give the pact his final approval.

Speaking at the National Assembly Friday, Deputy Prime Minister Sok An reaffirmed the government's commitment to silencing critics, saying "sensitive comments," such as calling the government traitorous, would contribute to political instability and had to be stopped.