WASHINGTON - US intelligence officials believe Libyan leader Muammar Gadhafi, who has not been seen in public since a NATO missile attack reportedly killed his son, is still alive, CIA Director Leon Panetta told NBC television on Tuesday.

"(The) best intelligence we have is that he's still alive," Panetta said in an interview with NBC News.

Gadhafi, who seized power in a 1969 coup, has not been seen in public since a NATO missile attack on Saturday struck a house in his compound in Tripoli. Libyan officials said Gadhafi survived, but his youngest son and three grandchildren were killed.

NATO could not confirm the reports that Gadhafi's son, Saif al-Arab Gadhafi, had been killed.

More than a month after Western powers began an air assault on Libya, fighting is dragging on between forces loyal to Gadhafi and poorly equipped rebels who had hoped to quickly force him from power.

Critics say NATO has already overstepped its mandate with Saturday night's attack on the Tripoli house. NATO insists it targets only military installations and was not attempting to assassinate the Libyan leader.