Kampuchea Krom activists are planning yet another round of demonstrations to protest remarks made by a Vietnamese embassy spokesman in June, demanding Prime Minister Hun Sen cut diplomatic ties with Vietnam until a public apology is issued.

The controversy – and a spate of on-again, off-again protests – stems from the spokesman's comment that southern Vietnam, known as Kampuchea Krom in Cambodia, had long been Vietnamese before it was ceded to that country by the French in 1949.

Thach Setha, president of the Khmer Kampuchea Krom Community, said at a forum in Freedom Park on Saturday the hypothetical end in relations would continue until "yuons apologise to Khmer, and if they still do not, we will demonstrate by boycotting Vietnamese products", using a term for Vietnamese considered derogatory by many.

Setha said that unless the spokesman apologises for "falsifying" history, a five-day round of protests will begin on October 1 with petitions delivered to the National Assembly and Hun Sen.

Authorities received a letter about the demonstrations and will consider whether they are legal, said Long Dimanche, City Hall spokesman.

Participants at the forum also discussed the recent census of ethnic Vietnamese in Cambodia, with many criticising it for being too lax.

Sok Sam Oeun, executive director of the Cambodian Defenders Project, took part in the forum and said immigration laws "have taken more than a decade to be implemented, but right now is just the beginning and they can be useful for our nation."