Syrian troops killed at least 100 people, opposition activists said on Tuesday, as the United States voiced support for a daily two-hour humanitarian ceasefire.

"Reprehensible actions taken by the Assad regime have led us to a situation where basic supplies, humanitarian supplies are very scarce," White House press secretary Jay Carney said.

"We support calls for ceasefires to allow for the provision of humanitarian supplies to Syrians who desperately need it," he added.

With President Bashar al-Assad's forces launching fresh assaults on the restive city of Homs and Idlib, near the border with Turkey, the International Committee of the Red Cross (ICRC) demanded the truce as a means to allow the delivery of urgently needed emergency aid.

"The current situation requires an immediate decision to implement a humanitarian pause in the fighting," said ICRC President Jakob Kellenberger in a statement issued in Geneva.

"In Homs and in other affected areas, entire families have been stuck for days in their homes, unable to step outside to get bread, other food or water, or to obtain medical care," Kellenberger said.

Late Tuesday activists said Syrian troops had attacked Idlib, killing at least 44 people. This is in addition to 56 people reportedly killed in intense shelling by government forces in Homs earlier in the day. About 300 shells were reportedly fired into the city and surrounding areas.

Rights groups say more than 6,000 people have been killed in the 11-month uprising against the Assad regime. Independent confirmation of such figures is impossible due to a government ban on most foreign journalists from reporting in Syria.

ccp/pfd (AFP, dpa, Reuters)