New Delhi - India's north-eastern state of Assam deployed thousands of additional police to stem clashes between Bodo tribals and Muslim migrants from Bangladesh that have claimed 40 lives and displaced as many as 80,000 villagers, officials said Monday.

The clashes erupted in Udalgiri and Darrang districts about 70 kilometres north of state capital Guwahati on Friday evening.

The violence spread to the Baksa and Sonitpur districts in the region and on Monday clashes between Muslims and the Rabhas tribe were reported from the western district of Goalpara.

"A total of 40 people were killed, 23 in group clashes while 17 died in police firing to quell the raging mobs," Assam Health Minister Himanta Biswa Sarma said from Guwahati by telephone.

"Some new deaths were reported in fresh clashes and more charred bodies were found in the worst-hit areas of Udalgiri and Darrang, where hundreds of houses were torched, raising the death toll," he added.

The state administration said there were reports of sporadic violence from different areas and the situation was "tense but under control."

Most of the victims were Muslims who had illegally migrated from neighbouring Bangladesh and settled on vacant land in Assam. The Bodos are an ethnic tribal people indigenous to northern Assam.

Over 80,000 people were forced to flee their homes as a result of the violence and were lodged in government-run relief camps in the districts, Sarma added.

State officials said an additional 2,600 police and paramilitary personnel were sent to the five restive districts where curfews had already been imposed.

Sarma said a Bodo militant group called the National Democratic Front of Bodoland (NDFB), that is fighting for an independent tribal homeland, was instrumental in triggering the violence.

"The violence is under planned ethnic cleansing by NDFB who want to drive out all non-Bodos from the area. We have already arrested some NDFB cadre in this connection who were involved in the killings," he added.

The NDFB is a majority Christian organization whose leader Ranjan Daimary is believed to be operating out of Bangladesh. The group had entered a ceasefire with the Indian government in 2005, but did not given up its independence struggle.

"We are investigating reports of the involvement of the NDFB in the clashes and if proved we shall be forced to call off the ceasefire," Assam Chief Minister Tarun Gogoi told the IANS news agency. (dpa)