The United Liberation Front of Asom (ULFA), one of the biggest rebel armies in the tea and oil-rich region of Assam, has been fighting for an independent homeland for ethnic Assamese since 1979.
At least 10,000 people, mostly civilians, have died in Assam because of fighting between government forces and the various rebel groups.
ULFA foreign secretary Sasha Choudhury told reporters in Guwahati, the largest city in Assam, that the group took "the decision to open unconditional peace talks at our general council meeting."
"We expect a mutually acceptable solution to the long standing Assam-India conflict," he said.
ULFA chairman Arabinda Rajkhowa is expected to lead the group at the talks on Thursday, an Assam state government official told AFP, requesting not to be named.
The government delegation will be headed by either home minister P.C. Chidambaram or by home secretary G.K. Pillai, the official said.
There was no immediate comment from the national government.
Most of the group's leaders are out on bail with the government facilitating their release from jail in order to pave the way for peace talks.
But the stance of ULFA's elusive commander-in-chief Paresh Baruah, said to be hiding in the Myanmar-China border area, remains unclear.
ULFA spokesman Choudhury said he was "sure Baruah would endorse our views. In fact, Paresh Baruah is bound to accept the general council meeting."
India has been wracked by separatist conflicts since its independence in 1947, with deadly insurgencies in its northwestern Kashmir region and the northeast.