The United States is wary of Libyan leader Muammar Gaddafi's stockpiles of mustard gas but there is no sign he intends to deploy chemical weapons, the top US military officer said today.

"It's something we're watching very closely," Admiral Mike Mullen, chairman of the Joint Chiefs of Staff, told CBS's "Face the Nation" programme.

"He does have (a) store of that, a significant quantity," Mullen said when asked if Libya had stockpiles of the dangerous chemical agent. "It's something he could do a lot of damage with."

Mullen made his remarks as an international coalition concluded the initial part of a military operation to halt an offensive by Gaddafi's forces on the rebel stronghold of Benghazi in eastern Libya.

The United States unleashed a barrage of strikes against the Libyan regime's air defenses, but has ruled out using ground troops in what President Barack Obama called a "limited military action."

US warships and a British submarine fired at least 110 Tomahawk cruise missiles into Libya against Gaddafi's anti-aircraft missiles and radar yesterday, the US military said.

A watchdog agency said last week that Libya still has over 10 tonnes of mustard gas years after signing a treaty banning chemical weapons, but has destroyed the weapons systems for using them.

Libya, which signed the Chemical Weapons Convention in 2004, has destroyed 55 percent of its mustard gas stockpiles but still possesses some 11.25 tonnes according to the Organisation for the Prohibition of Chemical Weapons.

Experts say Libya began eliminating its mustard gas stockpiles in early 2010 as scheduled and had continued to do so until unrest broke out in the north African nation last month.

Gaddafi committed to destroying the mustard gas, which can produce severe chemical burns to the eyes, skin and lungs, as part of an effort to end his diplomatic isolation several years ago.

Sign up to our free newsletters

Get the best updates straight to your inbox:
Please select at least one mailing list.

You can unsubscribe at any time by clicking the link in the footer of our emails. We use Mailchimp as our marketing platform. By subscribing, you acknowledge that your information will be transferred to Mailchimp for processing.