Cambodia's ethnic minority Khmer Krom monks and activists set a Vietnamese flag on fire here on Tuesday afternoon, as a protest to demand a Vietnamese diplomat to recognize the "true history" of the former Kampuchea Krom provinces entered the second day.

Nearly 200 protesters rallied outside the Vietnamese Embassy, which was fortified by anti-riot police and heavy steel barricades.

A video clip posted on the Facebook page of the Independent Monk Network for Social Justice showed a Khmer Krom monk and many activists burned the flag outside the embassy and they vowed to return for the third day protest if the Vietnamese diplomat fail to make a public apology.

Protests came after Trung Van Thong, a spokesman for the Vietnamese embassy to Cambodia, reportedly said in June that South Vietnam, or former Kampuchea Krom provinces, belonged to Vietnam prior to France's official transfer of the land in 1949.

"The purpose of our protest is to demand an apology from the Vietnamese spokesman and to urge him to accept the 'true history' of the former Kampuchea Krom provinces," Thach Sitha, president of the Khmer Kampuchea Krom Association, said Monday while leading the protest.

According to the history, French protectorate officially turned over the former Kampuchea Krom, once Cambodian territory, to neighboring Vietnam on June 4, 1949.

The Vietnamese Embassy to Cambodia last month issued a statement to condemn the protest, considering the move an act of intervention into the sovereignty and internal affairs of Vietnam.