Libyan leader Muammar Qaddafi has said he is in a place where NATO bombs "cannot reach" in an audio message broadcast on state television.
He also condemned as "cowardly" an attack on his compound in Tripoli on May 12.
Libyan officials said the strike killed three people.
NATO officials said a command-and-control bunker was hit.
Shortly before Qaddafi's remarks were broadcast, regime spokesman Moussa Ibrahim claimed that NATO had attacked Brega while dozens of imams and officials from around Libya were gathered there to pray for peace.
Ibrahim said 11 imams were killed in their sleep at a guesthouse, and 50 people were wounded, including five in critical condition.
The alliance, responding to the claim, said it had attacked a military command-and-control center.
Later, a NATO statement said that the alliance was "aware of allegations of civilian casualties in connection to this strike, and although we cannot independently confirm the validity of the claim, we regret any loss of life by innocent civilians when they occur."
NATO said on May 13 it had carried out 52 missions across Libya the previous day.
compiled from agency reports