Britain is sending up to 20 military advisers to help Libya's ragtag rebel force break a military stalemate with Moammar Gadhafi's army, even as NATO acknowledged Tuesday that its airstrikes alone cannot stop the daily shelling of the besieged opposition-held city of Misrata.

Gadhafi's troops have been pounding Misrata indiscriminately with mortars and rockets, a NATO general said, and residents reported more explosions and firefights in Libya's third-largest city. Hospitals are overflowing and 120 patients need to be evacuated from the city that has been under siege for nearly two months, the World Health Organization said.

The plight of Misrata's civilians and the battlefield deadlock are raising new questions about the international community's strategy in Libya. The leaders of the U.S., Britain and France have said Gadhafi must go, but seem unwilling to commit to a more forceful military campaign. NATO's mandate is restricted to protecting civilians.

Adm. Giampaolo Di Paola, chairman of NATO's military committee, said that even though the military alliance's operations have done "quite significant damage" to the Libyan regime's heavy weaponry, what Gadhafi has left is "still considerable."

Asked if more airpower is needed, Di Paola said any "significantly additional" allied contribution would be welcome.