The United Liberation Front of Asom, National Democratic Front of Bodoland and Kamtapur Liberation Organisation, under attack from the Royal Bhutan Army, have jointly called a 48-hour strike in Assam and parts of north Bengal from Saturday to protest against the killing of ULFA political advisor Bhimakanta Buragohain.

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In emails to media outlets in Guwahati, the three outfits said the Bhutan army launched its December 15 operation "without any clear ultimatum".

"The joint forces of Indian and Royal Bhutan Army are brutally killing old people, women and children," the joint statement alleged.

The forces, it said, did not give safe passage to octogenarian Buragohain, women and children in violation of Geneva Convention as well as all civil norms of modern war.