The United States and its Western allies launched air attacks on Libyan targets on Saturday, in what U.S. President Barack Obama described as the work of a "broad coalition" to protect "a threatened people" against ruler Moammar Gadhafi's forces.

"We are answering the calls of a threatened people and we are acting in the interests of the United States and the world," Obama said in a statement from Brazil, during a visit to Latin America.

"Make no mistake, today we are part of a broad coalition," Obama said. The Arab League has backed action against Gadhafi's forces, and while no Arab forces have joined the attack so far, "officials expect Arab countries will publicly announce their participation soon," the Pentagon said.

The Pentagon said 110 Tomahawk cruise missiles from U.S. and British ships and submarines had been fired at 20 targets. British jets also joined the attack, the government said early Sunday. The Western coalition is targeting Libyan air defences, especially around Tripoli and the west Libyan city of Misrata.

"This is the first phase of what will likely be a multi-phase operation," U.S. Vice Admiral William Gortney, director of the Pentagon's Joint Staff, said at a briefing in Washington after Obama spoke.

"These strikes were carefully coordinated with our coalition partners," Gortney said, adding that most of the targets — in what's being called Operation Odyssey Dawn — were on the Mediterranean coast and that information was still coming in because it was night.

Responding on Libyan state television to the attacks, Gadhafi warned that the coalition action has turned the Mediterranean region and North Africa into a "ground of war."

Gadhafi said he would open his country's military stores to "arm all the masses with all types of weapons" in defence of the country against a "colonial crusader."

An Al Jazeera reporter in the rebel capital Benghazi, meanwhile, said that people there were firing guns in the air to celebrate the international attacks.

Al Jazeera also reported that one of the targets hit was a military college near Misrata, where it said Gadhafi's forces were believed to be based.

Libyan TV, controlled by the government, said the attacks had killed 48 people and wounded 150.

Canadians getting ready

Prime Minister Stephen Harper said earlier Saturday that Canadian aircraft would be participating in extensive aerial operations "very soon" to protect civilians, but a spokesman for the Prime Minister's Office said the jets had just arrived in the region and needed up to two days to prepare for any missions.

Elsewhere, British Prime Minister David Cameron confirmed that British forces are also in action over Libya.

"What we are doing is necessary, it is legal, and it is right," Cameron told reporters in London.

French airstrike

Earlier in the day the coalition action began with a French airstrike that happened at 6:45 p.m. local time in Libya (4:45 p.m GMT), French Defence Ministry spokesman Thierry Burkhard said.

Who's sent what: United States Guided-missile destroyers and submarines, two amphibious warships, command-and-control ship and aircraft based in Italy. Canada Six F-18 Hornets sent to Italy and HMCS Charlottetown, a frigate, is in the Mediterranean. France Eight Rafale and four Mirage jets.

Six C-135 refueling tankers.

One AWACS surveillance plane.

Sending the aircraft carrier Charles de Gaulle to the region. Denmark Six F-16s in Sicily. Italy Offered use of seven military bases.

Has 10 aircraft available to fly on 15 minutes notice.

Aircraft carrier Giuseppe Garibaldi off Sicily Spain Four F-18s and a Boeing 707 refueling plane sent to Italy.

Submarine, frigate, surveillance plane deployed. Britain Typhoon and Tornado planes sent to jets to participate in attacks.

Two frigates and a missile-firing submarine are off Libya's coast. Norway Offered six F-16s. — AP

At least one Libyan armoured vehicle was destroyed in the attack, a French official said. Al Jazeera said the attack happened southwest of Benghazi.

The attack followed a meeting Saturday called by French President Nicolas Sarkozy. He said the 22 leaders from Europe, the Arab League and the UN agreed on the strike.

Early Saturday, there were reports that forces supporting Gadhafi were trying to enter Benghazi, launching attacks in defiance of a UN no-fly resolution. But by late Saturday, Gadhafi's forces had pulled back, Al Jazeera said.

Warplanes could be heard overhead, the shelling had stopped and city residents began to flee, The Associated Press reported.

Thousands flee

Thousands of Libyans were fleeing shelling on the western side of Benghazi, the CBC's Nahlah Ayed reported from Cairo.

Long lines of traffic were reported heading east on the road from Benghazi to the city of Tobruk, and long waits were also happening at gas stations.

As well, video footage from the city showed a jet being shot down over the city. An Associated Press reporter saw the plane go down in flames and heard the sound of artillery and crackling gunfire.

Libya's government denied there had been any action in Benghazi and blamed rebel elements for trying to spark international military action.

"There are no attacks whatsoever on Benghazi," government spokesman Mussa Ibrahim told Reuters.