The Indian military and separatist rebels in the north-eastern state of Manipur have made conflicting claims about battles near the Burmese border.
By Subir Bhaumik
BBC correspondent in Agartala, north-east India
The Indian army is trying to take control of the Sajit Tampak area in Manipur's Kandu district, where three Manipuri separatist groups have bases.
At least 19 rebels were killed in the last four days, army officials say.
But the Manipur People's Liberation Front told the BBC rebel fighters have beaten back a military offensive.
A spokesman for the front, which is made up of three separatist groups in the state, said not less than 20 soldiers have died.
Last year, the Indian border security force failed to dislodge the rebels from Sajit Tampak and ended up suffering heavy casualties.
Both sides agreed that the recent fighting at Sajit Tampak had been heavy, despite incessant rains in the area.
The military offensive started early this week; a core commander of the Indian army, Lieutenant General Daljit Singh, is in Manipur to supervise the operation.
But local correspondents say that the army's efforts to take control of the remote hill region bordering Burma have been affected by bad weather which has made air support difficult to come by.
Last year, the rebels beat back a similar offensive by the border security force with heavy casualties.
Intelligence officials say the remoteness of Sajit Tampak helps the rebels and its proximity to Burma makes it possible for them to bring in a huge quantity of weapons and ammunition from across the border.