Police have arrested two Khmer Kampuchea Krom suspects following a blast at the Vietnamese Friendship Monument in Phnom Penh Sunday.
Kim Toeun, 53, a construction worker and former Khmer Rouge brigade chief, and Son Than, 42, of unknown profession, are being held in Phnom Penh.
Both were once members of the Khmer Kampuchea Krom Liberation Front, said Ministry of Interior chief of information, Chhay Sinarith.
Police compared the act, which left behind two unexploded TNT-fertilizer bombs, to political activities such as those conducted by the Cambodian Freedom Fighters, who had a shootout with police in Phnom Penh in November 2000.
Chhay Sinarith called the incident a political threat to the Cambodian government but stopped short of calling it a terrorist attack.
"We see that the characteristics are not of a terrorist nature like in other countries, [especially] in the Middle East," he said. "We see that those explosions caused people's deaths. But these activities are more political in nature."
In recent weeks members of the Khmer Krom ethnic minority have complained of discrimination and detention in Vietnam.
The rights of the group has been at the center of several violent demonstrations lately, and one Khmer Krom monk recently disappeared after being defrocked in what rights groups fear was a forced expulsion to Vietnam.