SAO PAULO: Five members of an Indian tribe in Brazil's Amazon region have been arrested on suspicion of kidnapping and killing three outsiders, police said on Friday.

The case that has already led to clashes between the indigenous group and families of settlers.

A federal police officer said by telephone that there was still no sign of the three men who disappeared as they were driving through the Tenharim reservation in December.

But he said witness testimony as well as evidence from the car in which they were believed to be traveling indicates they were killed.

Members of the tribe, which consists of fewer than 1,000 people, deny they killed anyone.

The officer said the Tenharim men apparently attacked the three in retaliation for what they believed was the murder of one of their leaders, Ivan Tenharim, on December 3.

Police said at the time he died in a motorcycle accident, but members of the group say they want the death investigated further.

The officer declined to be identified because he was not authorised to speak to the press.

On December 25, angry farmers, convinced that Tenharim Indians had kidnapped the three nine days earlier, torched several Tenharim huts and the offices of the federal Indian affairs agency, as well as several of its vehicles and river boats.

More than 100 Indians sought refuge inside an army compound and only returned to their reservation six days later when elite police were sent in to protect them.

Indigenous groups in Brazil often clash with farmers and loggers they say encroach on their ancestral lands.

According to the Roman Catholic Church-backed Missionary Indigenous Council, 560 Indians were slain from 2003 to 2012, most of them in fights over land with farmers and ranchers.