By Subir Bhaumik BBC east India correspondent

A senior separatist leader, his aide and a bodyguard have been killed by Indian soldiers in the north-eastern state of Assam.

Military officials said the troops raided the hideout of the outlawed United Liberation Front of Assam (Ulfa) in Ghagrapar just after sunrise, and were involved in a fierce encounter with the rebels.

Ghagrapar is in Assam's central district of Nalbari, where the Ulfa has a strong presence.

Major General Gaganjit Singh said his troops killed Dipak Das, who headed the so-called Enigma unit of the Ulf, during the encounter.

His secretary and his bodyguard were also killed by the troops, who said they discovered two weapons and 16 kilograms of top grade explosives at the hideout.

Violent history

The Enigma unit is responsible for all acts of sabotage, explosions and select assassinations that the Ulfa has undertaken in the past.

Senior politicians, including ministers of the state government and military officials, are among those who have been killed by the Enigma unit.

Major General Singh said Dipak Das was a close associate of the Ulfa's military wing chief, Paresh Barua.

Mr Barua is believed to be opposed to peace talks between the Ulfa and the Indian Government.