The United States has imposed sanctions against Libyan Prime Minister and four other top officials besides two companies controlled by the children of President Muammar Gaddafi. Announcing this in Washington the acting Under Secretary for Terrorism and Financial Intelligence, David Cohen said the US will continue to expose and impose sanctions on senior Libyan government officials who choose to remain on Gaddafi's side. Meanwhile, heavy fighting was reported in and around Misrata, the only city in the west Libya that remains under rebel control. It is the third largest city, situated 160 kilometers from capital Tripoli, and has strategic and symbolic significance. It has been under siege by government troops for weeks. In another development, NATO confirmed its warplanes bombed tanks belonging to the rebels near the eastern oil city of Brega.