MAOIST rebels fighting to overthrow Nepal?s constitutional monarchy killed six policeman and wounded 11 in the biggest attack on security forces in the Himalayan kingdom in a month, officials said yesterday.

The attack took place on Tuesday night in Kailali district, 600 km (375 miles) west of the capital, Kathmandu, district administrator Sibendra Purush Dhakal said. The area is a Maoist stronghold.

The rebels ambushed the patrol, throwing crude bombs and opening fire with rifles, as the policemen were going through a forest. ?There was a fierce battle and many Maoists could have also been killed,? an army officer said.

The rebels, who follow the teachings of the late Chinese leader Mao Zedong, have been fighting to set up a communist republic since 1996. More than 8 100 people have been killed.

Violence has increased since August when peace talks collapsed after the government rejected a rebel demand for a new constitution to curb the role of monarchy.

Officials say the rebels, who until recently were most active in Nepal?s Himalayan foothills, are now mounting attacks in cities and on the southern plains, the country?s main business and industrial area along the border with India.

The violence has hurt the country?s important tourism sector although the rebels have said they have no intention of attacking foreign mountaineers, trekkers and other visitors. In the last big rebel attack, 10 soldiers were killed in an ambush on November 2.