MOSCOW - Russia's Foreign Ministry said on Sunday that NATO could be targeting leader Muammar Gadhafi and his family, after Libyan officials said his youngest son and three grandchildren were killed in an air strike.

Russia has been an outspoken critic of the Western military alliance's intervention in Libya.

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Earlier, Russian parliament member Konstantin Kosachev told Interfax news agency the attack was proof the coalition was not protecting civilians, as mandated by the United Nations.

"We have serious doubts about statements by the coalition members that attacks on Libya are not intended to physically eliminate Gadhafi and his family," the ministry said in a statement.

NATO denied targeting Gadhafi or his family in the Saturday evening bombing, but said it had launched air strikes on military targets. Libyan officials said there had been an "assassination attempt".

Libyan government spokesman Mussa Ibrahim said Gadhafi's youngest son Saif al-Arab, 29, was killed in the attack along with three of Gadhafi's grandchildren.

Russia's Foreign Ministry echoed its plea of a week ago for an immediate ceasefire and the "beginning of a political settlement without any preconditions".

"Moscow is treating the reports about civilian casualties with growing concern," it added.

The Libyan rebels and NATO have rejected Gadhafi's offer for a ceasefire, saying it lacked credibility.

Russian Prime Minister Vladimir Putin has criticised the Western countries enforcing a no-fly zone over Libya and said they have gone beyond the limits of a UN Security Council resolution designed to protect civilians.

Russia holds the power of veto as a permanent member of the Security Council but abstained in March in a vote on a resolution authorising force to protect civilians.