Jakarta – Police have arrested both a leader of the ethnic Dayaks who killed more than 500 settlers on Borneo island this year, and the commander of a Muslim militia fighting Christians in the Maluku islands, officials said yesterday.

Jafar Umar Thalib, commander of the Laskar Jihad, or Holy War Troops, was detained yesterday over allegations that he incited violence in the eastern Maluku islands, a spokesman for the group said.

More than 5,000 people have been killed in the province since fighting between Muslims and Christians first erupted there in 1999. The conflict intensified after the 3,000-strong paramilitary group arrived in the region last year.

Jafar and other Laskar Jihad leaders have vowed to rid the islands of Christians. Local officials blame the fighters for some of the bloodiest incidents in the war.

Meanwhile, police on Borneo island arrested Mohammad Usop, a university professor, on charges of inciting ethnic violence in which more than 500 immigrants from the island of Madura were killed, a spokesman said.

Mohammad Usop, 64, the respected head of the Dayak Community Research Association in Palangkaraya, was arrested and flown to Jakarta on Thursday as "a suspect in last February's massive violence" in central Kalimantan.

He is being held on charges of inciting the bloodshed, a crime that carries a maximum sentence of six years in jail. Mohammad is also the former rector of Palangkaraya University in the central Kalimantan provincial capital of Palangkaraya on Borneo island.

One of his staff, speaking to AFP on condition of anonymity, called the arrest "ethnically biased, and simply because of his outspokenness".