Forces loyal to Libyan leader Muammar Gaddafi have fired several Scud missiles from the regime's bastion of Sirte at rebel-held Misrata further up the coast, a rebel source said.
"Scuds launched from Sirte towards Misrata, loud explosions heard," the media centre of the Misrata military council said in a statement on Tuesday night.
There were no further details and the report was not confirmed by any independent source.
On Tuesday NATO officials said one of the unguided rockets had been fired at Misrata from the neighbourhood of Sirte, Gaddafi's birthplace, the previous day.
It "landed in the coastal area of Misrata, most likely in the sea or on the shore", chief NATO spokeswoman Oana Lungescu said, adding "we are not aware of damage or casualties".
The United States and NATO said on August 15 that Gaddafi forces had used the Scud for the first time since NATO began an air campaign against the regime on March 19, firing one from Sirte eastwards towards Brega but causing no damage.
Libya has an estimated 240 of the ballistic missiles in its arsenal, and its "Scud B" model has a range of about 300km, according to the Jane's Defence military journal.
Rebel forces have taken control of much of Tripoli and are advancing on Sirte from east and west.
Negotiations began Tuesday with local tribes in a bid to secure a peaceful surrender.
