Suspected separatist guerrillas killed 18 Bengali settlers in two attacks Thursday in a remote part of northeastern India plagued by tensions between local tribes and recent migrants.

Several other settlers were wounded in the attacks in Tripura state (search), where several tribal groups have been fighting to evict tens of thousands of migrants from Bangladesh and the neighboring state of West Bengal (search).

No group immediately claimed responsibility, but police blamed the attack on the All Tripura Tiger Forces (search), an outlawed rebel group that has been fighting for a separate tribal homeland.

The tribal groups accuse the Bengali settlers of exploiting Tripura's resources and depriving its native population of the benefits of economic development.

The attackers raided Borolunga, a remote village 30 miles northeast of Agartala (search), Tripura's capital, and fired indiscriminately at the local residents, killing at least 12 of them, said D. Gautam, a top police officer, when reached by the phone.

"We are yet to ascertain the exact death toll and the number of wounded. First reports reaching us say that at least 12 people were killed in this attack," Gautam told The Associated Press.

Fifteen minutes later, suspected rebels struck in the nearby village of Daspara and gunned down another six people, Gautam said.

At least 11 separatist groups in India's northeast have called for a strike during Friday's celebrations marking India's independence from Britain in 1947. The rebels asked citizens of the region to boycott all government functions and to refrain from any celebrations.

The rebels oppose Indian sovereignty in the region and accuse New Delhi of exploiting the natural resources of the northeast, rich in oil, minerals, tea and timber.