TRIPOLI (Reuters) - British and French attack helicopters struck inside Libya for the first time overnight on Saturday, hitting targets in the oil port of Brega as NATO forces stepped up their air war against Muammar Gaddafi. Aircraft of the NATO-led alliance also hit targets in Tripoli, where at least six powerful explosions were heard. A Reuters correspondent in the Libyan capital said aircraft could be heard overhead at the time of the blasts, before sunset. It was not immediately clear which targets were hit. "As long as Gaddafi continues to abuse his people, we will continue and intensify our efforts to stop him from doing so," British Foreign Secretary William Hague said at a news conference in the rebel stronghold of Benghazi in eastern Libya. Speaking in Benghazi shortly before Hague's arrival, the head of the rebel council Mustafa Abdel Jalil welcomed NATO's deployment of helicopters. "We welcome any measures that would expedite the departure of Gaddafi and his regime," he told reporters in Benghazi, where Hague later arrived for talks with council members. Hague visited the square next to Benghazi's court house where people greeted him by waving the victory sign and shouting: "Libya free" and "Gaddafi go away" A NATO-led military alliance extended its mission to protect civilians in Libya for a further 90 days this week, and France said it was stepping up military pressure as well as working with those close to Gaddafi to try to persuade him to quit. "This was the first operational mission flown by British Army Apaches at sea," British Defence Secretary Liam Fox said. "The additional capabilities now being employed by NATO further reinforce the UK's enduring commitment and NATO's determination to ... ensure that the people of Libya are free to determine their own future." Military analysts say attack helicopters will allow more precise strikes against pro-Gaddafi forces hiding in built-up areas than the high-flying jets used so far, while reducing the risk of civilian casualties. But given the vulnerability of helicopters to ground fire, their deployment also increases the risk of Western forces suffering their first casualties of the campaign. Critics of the war have warned of "mission creep" but NATO has said the use of helicopters would not presage the deployment of ground troops.