Security forces killed six suspected insurgents Tuesday in a gunbattle in southern Thailand.

The 20-minute fight Tuesday afternoon came as a combined force of police and soldiers laid siege to a house in Pattani province, which along with neighboring Yala and Narathiwat has been the scene of a Muslim separatist insurgency since 2004.

Police and soldiers, who surrounded the house with a force of about 200 after following a suspect there, first asked the men to surrender, but received no response. Two police officers were wounded in the fighting.

No suspected insurgents were taken into custody or were known to have escaped. Two assault rifles, one pistol and a hand grenade were found inside the house. Police said they were checking the identities of the dead men, but believed all were subjects of arrest warrants. They believe one of them was Arhama Duramae Pa-do, suspected of shooting a policeman last year.

More than 3,700 people, both Muslims and Buddhists, have been killed in Thailand's three southernmost provinces since the insurgency flared in January 2004. The provinces are the only Muslim-majority areas in the predominantly Buddhist country. Muslims there have long complained of discrimination by the central government.

A massive security presence has failed to stop the violence. Militants target both Buddhists and Muslims working with the government, including soldiers, police and suspected informants. They also stage attacks on civilians that are believed to be intended to scare the Buddhist community into fleeing.

The insurgents have made no public pronouncements but are thought to be fighting for an independent Muslim state. The area used to be an Islamic sultanate until it was annexed by Thailand in the early 20th century.