Forces fighting for Muammar Gaddafi fired three Scud missiles this evening, a US Defence Department official and Nato confirmed.
The missiles was fired from Sirte, the Mediterranean port city located between Tripoli and Benghazi and appeared targeted at the rebel-held stronghold of Misrata. They landed in the sea or the desert.
Another Scud was fired by Gaddafi forces last week and missed the oil town of Brega.
Sirte, which was Gaddafi's birthplace and remains a stronghold of support, was bypassed by rebels as they advanced on Tripoli.