Maoist rebels in Nepal say the government must agree to an assembly that would rewrite the constitution or the rebels will consider peace talks over.
A statement from chief rebel negotiator Babu Ram Bhattarai reportedly gives the government three days to comply with the rebels' demand.
The statement did not specify whether the Maoists are threatening to withdraw from a seven-month-old cease-fire agreement as well.
Negotiations between the rebels and the government collapsed last week. Friday, U.S. officials called on the rebels to continue the cease-fire and urged both sides to show good faith in working toward a peaceful resolution.
The rebels have been fighting since 1996 to abolish Nepal's constitutional monarchy and replace it with a communist state. More than 7,000 people have died in the fighting.