Nato Secretary General Anders Fogh Rasmussen has told a foreign ministers' summit the alliance needs "a few more" aircraft for its mission in Libya. Mr Rasmussen said he had received no offers from any ally at the meeting in Berlin to supply the extra warplanes, but he remained hopeful. Nato would continue "day by day, strike by strike" to target Col Muammar Gaddafi's forces, he told media. Britain and France have been trying to persuade other Nato members to do more. London and Paris have been urging allies to get actively involved with ground attack planes to intensify air raids, says BBC diplomatic correspondent James Robbins, who was at the Berlin news conference. Blasts rock Tripoli There are divisions in the alliance, with Turkey and Germany opposed to the Libya mission. Mr Rasmussen told the meeting that Nato supreme commander Adm James Stavridis was "generally content" with his forces. But the secretary general added: "Now they [pro-Gaddafi forces] hide their heavy arms in populated areas where before many targets were easy to get to. "To avoid civilian casualties we need very sophisticated equipment so we need a few more precision fighter ground attack aircraft for air-to-ground missions." He added: "I am confident that nations will step up to the plate," although when pressed, he said he had received "no specific pledges or promises from this meeting". As Mr Rasmussen spoke, Nato warplanes bombed targets in the Libyan capital, Tripoli. A BBC correspondent in the city said there were two loud blasts, followed by plumes of smoke rising into the sky. Our correspondent says a military installation near Nasser University may have been the target. The raids were followed by heavy anti-aircraft fire. Fighting has continued in the rebel-held city of Misrata, western Libya, which has been besieged by pro-Gaddafi forces for nearly two months. A rebel spokesman told Reuters news agency that a rocket attack by pro-Gaddafi forces killed 23 people on Thursday morning. Koussa sanctions lifted Some assessments suggest that Nato only needs about a dozen or so extra strike aircraft to maintain the tempo of operations. Only a few of Nato's 28 members - including France, the UK, Canada, Belgium, Norway and Denmark - are conducting air strikes. The US has scaled back its role in Libya, though on Wednesday it said its jets were still carrying out bombing raids on Libya's air defences to enforce a UN-mandated no-fly zone. Several major Nato member countries, including Spain and Italy, have not taken part in attacks on ground targets. Spain said on Thursday it would continue to provide aircraft without joining directly in such raids. Italy is also refraining from carrying out air strikes, but it allows missions to be flown from its territory. Meanwhile, Moussa Koussa, the Libyan foreign minister who fled to the UK late last month, is no longer subject to EU sanctions, the British government said. Mr Koussa is a former head of Libyan intelligence and has been accused of involvement in the 1988 Lockerbie bombing. Earlier, Russian President Dmitry Medvedev reiterated Moscow's view that the UN resolution on Libya did not authorise the use of force. He was speaking at a meeting of the "Brics" group of five emerging nations - Brazil, Russia, India, China and South Africa. After the meeting in China, the five said they shared "the principle that the use of force should be avoided". Source: BBC