The government and Nagas are expected to decide on extending the 10-year-old ceasefire in Nagaland in their talks to be held in Dimapur on July 30-31 amid indications that the rebels have hardened their stance on the demand for "sovereignty".

The NSCN-IM's move to insist on another round of talks on extending the truce, which ends on July 31, is being seen in the Union home ministry as part of pressure tactics to get the government to agree to its controversial demands, including the unification of Naga-inhabited areas of the northeast.

There were indications that the ceasefire could be extended only for six months, unlike last July's one year.

Though top rebel leader V S Atem said talks between the NSCN-IM and government on Friday were held in a very positive atmosphere and both sides respected each other's position, sources said the rebels had hardened their position on the key sovereignty issue and sought a commitment from the Centre on it.

"The issues of unification of Naga-inhabited areas and sovereignty indeed figured in the discussions," a senior NSCN-IM leader said.

Sources said the rebels wanted to know why the ceasefire should be extended if it "did not serve any purpose". They questioned New Delhi's response to their proposals made six years ago for a settlement raised queries about what the government is willing to commit to the Nagas, the sources said.

The answers to these questions, they said, will decide the fate of the ceasefire between the NSCN-IM and the government.