The Syrian government's chief negotiator said his team was pushing for an expanded government led by President Bashar Assad at U.N.-led peace talks, and Assad's own future was not up for negotiation.

Bashar Ja'afari told Lebanese TV news channel al Maydeen the larger government they wanted would preserve all the country's existing institutions.

"In Geneva we have one mandate only to arrive at an expanded national government only, this is our mandate ... this is the goal we strive to achieve in the Geneva peace talks," Ja'afari said in comments broadcast overnight.

The Western-backed Syrian mainstream opposition decided on Monday to take a pause in peace talks saying the Syrian government was not serious about moving towards a U.N.-backed political process they say would bring a transitional governing body with full executive powers without Assad.