The U.N. mission to Libya is calling for a weeklong cease-fire in the capital, Tripoli, where forces loyal to a military commander are battling militias loosely allied with a U.N.-supported government.

The U.N. mission says the "one-week humanitarian truce" would begin at 4 a.m. (0200 GMT) Monday. It is calling on all parties to cease military operations, including reconnaissance and mobilization.

It was not immediately clear if any of the factions in Tripoli had agreed to the truce, which would come as many Muslims across the world begin observing the fasting month of Ramadan.

Field Marshal Khalifa Hifter's forces launched an offensive in Tripoli in early April. The fighting has killed nearly 400 people and wounded nearly 2,000. The U.N. has repeatedly called for a halt to the fighting.