A rebel group in India's north-east says it has lost six mobile bases in Burma during a major offensive begun at the weekend by Burmese troops.
By Subir Bhaumik
BBC News, Calcutta
The National Socialist Council of Nagaland (Khaplang faction) said about 8,000 Burmese soldiers were involved.
The rebel group is one of more than 20 fighting for greater independence or tribal rights in India's north-east.
Burma's military ruler, Than Shwe, on a recent trip to Delhi vowed to fight separatists operating from Burma.
Kughalo Mulatonu, a leader of the Khaplang faction of the National Socialist Council of Nagaland (NSCN), said pitched battles had been fought in the past few days between fighters of his group and Burmese troops.
Mr Mulatonu said his faction had lost six mobile bases in the fighting with three Burmese brigades in Burma's remote western region of Sagaing.
Indian military officials said Burmese troops had attacked rebels from Nagaland and Assam with renewed vigour after the first attacks were beaten back at the weekend.
Burma is silent on the offensive and details of casualties during the fighting are not available.
The attacks coincide with a month-long drive by about 6,000 Indian troops against rebels in the north-eastern Indian state of Manipur.
The Indian army says it has overrun several bases of insurgents there although the rebels say all of their important bases are intact.
Indian military officials say they are trying to co-ordinate the counter-insurgency offensive with Burmese troops but deny this is a joint operation.
"We are on our own but our objectives are the same," said one general in India's eastern army who did not want to be named.
Separatist violence covers seven states in north-eastern India. More than 200 ethnic and tribal communities and more than 20 rebel groups are fighting for greater degrees of independence or tribal rights.