Cambodian government officials say two of the three remaining top leaders of the Khmer Rouge guerrillas have surrendered.

They are Khieu Samphan, who for a while was the nominal leader of the group, and Nuon Chea, the shadowy figure behind the Khmer Rouge's extreme left-wing ideology.

But officials said they were not joined by Ta Mok, known as the brutal strongman responsible for many of the Khmer Rouge purges.

Earlier this month, several hundred Khmer Rouge fighters surrendered in their former stonghold along the Thai border.

The Cambodian government said they were the last remnants of the organisation which ruled the country for three years in the 1970s, and was responsible for the deaths of up to two million people.