Ninety-seven lawmakers voted for the pact by raising their hands following some eight hours of heated debate, with none against. But 14 lawmakers from the opposition Sam Rainsy Party walked out of the National Assembly session before the vote in protest of the agreement.
"It is a very sad day for our nation," said Son Chhay, an opposition party lawmaker. "It looks like we are begging Vietnam to stop taking more (Cambodian) land and just trying to put up a fence to circle what is left."
Prime Minister Hun Sen signed the pact with Vietnamese leaders during his visit to Hanoi last month. Its ratification, Hun Sen told reporters Friday, shows the "very high responsibility" of the legislature.
He added that the government intends to establish a "precise" border line between Cambodia and Vietnam and "make it a border of peace, friendship and cooperation for development."
Border issues are a passionate subject for many Cambodians, who have seen the vast territory once ruled by their ancient Angkor Empire swallowed up over the centuries by their larger neighbors, Vietnam and Thailand.
The controversy heated up again when Hun Sen signed the new border treaty with Vietnam that critics said gave up land to which previous Cambodian governments had staked a claim.
Hun Sen has sued at least six Cambodians for criminal defamation after they criticized the deal. Two of them, a radio station director and a union leader, are in jail pending trial.
Border issues with Vietnam are especially contentious, since Hanoi's troops occupied Cambodia for a decade after they toppled the Khmer Rouge regime in 1979. Hun Sen was foreign minister under the Vietnamese-installed communist government in the 1980s and then prime minister. I.L.