Britain and France say NATO must intensify its air campaign in Libya to protect civilians by destroying the heavy weaponry used by government forces.
French foreign minister Alain Juppe says civilians remain at risk and NATO's efforts have not gone far enough.
Britain's foreign secretary William Hague has echoed the comments and repeated his call for Libyan leader Muammar Gaddafi to step down.
Libyan rebels opposing Col Gaddafi have been pushed back despite the air raids, the BBC reports.
Pro-Gaddafi forces launched fresh artillery attacks on the rebel-held city of Misrata on Tuesday.