TRIPOLI: Powerful explosions rocked Tripoli Tuesday as NATO unleashed its heaviest blitz yet of the capital, while top United States official Jeffrey Feltman said that Libya's rebels are to open a representative office in the US and that Washington sees them as “credible and legitimate representatives of the Libyan people”. The shockwave from the strikes was so powerful that plaster fell from the ceilings in a hotel where foreign reporters were staying, about two miles from Gaddafi's compound. A NATO official said the strikes hit a military facility that had been used to attack civilians. A Libyan government spokesman said three people had been killed and 150 wounded, and that the casualties were local residents. Libyan government spokesman Mussa Ibrahim said the strikes had targeted a compound of the Popular Guards, a tribally based military detachment. But he said the compound had been emptied of people and “useful material” in anticipation of an attack. “This is another night of bombing and killing by NATO,” Ibrahim told reporters. On Monday, Washington urged Gaddafi to leave Libya as Feltman, the US Assistant Secretary of State for Near Eastern Affairs, held talks in the rebel capital Benghazi. Feltman told a media conference in Benghazi on Tuesday that the rebels' National Transitional Council had been invited to open an office in Washington. “I delivered a formal invitation to the council for the opening of a representation in Washington,” Feltman said. “This step is an important milestone... and we are happy they accepted it,” he added. On the issue of calls for US recognition of the NTC as the “sole legitimate interlocutor” of Libyans, Feltman noted the council was in fact already the only representative of the country in Washington.“We have a special envoy in Benghazi. President Obama has just invited the NTC to establish a representative office in Washington,” he said. “We have no office in Tripoli now. And we asked the Gaddafi people to close their embassy in Washington. “Our officials see members of the council, the council sees us,” said Feltman. “There is ongoing diplomatic, political relationship and dialogue with members of the council who are considered by our fellows credible and legitimate representatives of the Libyan people.” Britain, France, Gambia, Italy and Qatar have already recognized the rebel council as their sole interlocutor in Libya.