South African President Jacob Zuma says the Libyan government has accepted an African Union peace proposal to end the eight-week-old conflict.
Mr Zuma's AU delegation met Libyan leader Col Muammar Gaddafi in Tripoli on Sunday. An AU team is going to the eastern rebel stronghold of Benghazi.
But rebel spokesmen said there could be no truce unless Col Gaddafi stepped down and his forces withdrew.
In Ajdabiya, pro-Gaddafi forces have pushed back rebels in fierce fighting.
Nato says its planes destroyed 25 government tanks on Sunday alone.
The alliance said it had "taken note" of the AU initiative and welcomed efforts to save Libyan civilians.