The National Assembly of Cambodia on Thursday ratified a protocol on the investment promotion and protection agreement between the governments of Cambodia and Vietnam.

All 64 lawmakers of the ruling party, who were present at the parliamentary session, unanimously approved the protocol as the opposition party's 55 lawmakers-elect continued boycotting the parliament in protest against the election results in July last year.

Mok Mareth, chairman of Commission on Investment, Agriculture, Rural Development, Environment, and Water Resources at the National Assembly, said the protocol was part of ensuring confidence of investors and facilitating investment between the two countries.

"Under this protocol, Cambodia will move a step forward to attract investment from Vietnam and gain more confidence from Vietnamese investors," he said.

Sok Chenda Sophea, secretary general of the Council for the Development of Cambodia, said the protocol was aimed to maintain, promote and facilitate investment affairs between the two neighbors.

"A lot of Vietnamese investors are doing businesses in Cambodia, " he said, adding that the protocol would help maintain existing Vietnamese investors and attract more new investors.

Vietnam is the fifth biggest investor in Cambodia, with 128 projects worth over 3 billion US dollars by 2013, according to the Association of Vietnamese Investors in Cambodia.