Forces loyal to Colonel Muammar Gaddafi have used scud missiles for the first time since the uprising against his rule began six months ago.
News agencies quoted unnamed US defence officials as saying a Scud missile landed east of the rebel-held oil town of Brega.
The same sources said the missile landed in the desert and that there were no casualties. It is unclear what Gaddafi might have been targeting.
Ramadan El-Shekhi, a resident of the rebel stronghold of Benghazi, described the Libyan leader of almost four decades as “a man without any morals” who wanted to maintain power at any cost.
“He has lost everything now and his regime is approaching its end,” El-Shekhi said.
Gaddafi’s stockpile of Soviet-era scud missiles have an estimated range of 300 kilometres. US defence officials say the attack on Brega was launched from his hometown of Sirte.
Both the United Nations and rebels have denied media reports that they are talking with Gaddafi’s government on the Tunisian island of Djerba to try to end the six-month conflict.