BENGHAZI, Libya (AP) - British and French attack helicopters struck for the first time inside Libya, giving the NATO campaign more muscle against Moammar Gadhafi's forces. Hours later, Tripoli was hit by another round of airstrikes and at least eight explosions sounded in the capital.

The use of helicopters significantly ramped up NATO's operations and was a major boost to Libyan rebels, just a day after the fighters forced government troops from three western towns and broke the siege of a fourth. It was yet another erosion of Gadhafi's power since the eruption in mid-February of the uprising to end his 42-year rule.

NATO said the helicopters struck troops trying to hide in populated areas, military vehicles and equipment. Lt. Gen. Charles Bouchard, commander of the Libya operation, said the engagement "demonstrates the unique capabilities brought to bear by attack helicopters."

Until now, NATO has relied on attack jets, generally flying above 15,000 feet (4,500 meters) - nearly three miles (five kilometers) high. The jets primarily strike government targets but there have been cases where they missed and hit rebels instead.

The helicopters give the alliance a key advantage in close-up combat, flying at much lower altitudes.

The British Apaches hit two targets near the eastern oil town of Brega, according British Maj. Gen. Nick Pope, and separate Royal Air Force aircraft destroyed another military installation near Brega and two ammunition bunkers at the large Waddan depot in central Libya.

Brega is of strategic importance to Libya's oil industry and lies on the coastal road along the Mediterranean that leads to the capital, Tripoli. In the early days of the uprising against Gadhafi, it went back and forth between rebel and loyalist hands, but later the front line settled to the east of the town, leaving Brega under Gadhafi's control.

The French Gazelle and Tiger helicopters struck 15 military vehicles and five military command buildings, said Col. Thierry Burkhard. All the helicopters returned safely, the French and British said.

British Defense Secretary Liam Fox said the "use of the attack helicopters is a logical extension" in NATO's campaign and indicated more would be used in the future.

"We will continue with the methods we have to degrade his (Gadhafi's) command and control, to degrade his supplies," Fox said from Singapore, where he was attending an Asian security conference.