Syria: US backs Red Cross call for truce
The US has backed calls by the Red Cross for a humanitarian ceasefire in Syria to allow aid to reach the worst affected areas.
The White House said "reprehensible actions" by the Syrian government meant basic supplies were "very scarce".
The Red Cross says it is negotiating with both sides for a daily truce of at least two hours.
Meanwhile, Syrian activists say at least 100 people have been killed in the latest clashes.
Witnesses say Syrian forces loyal to President Bashar al-Assad have also intensified their attacks on rebel-held areas of the restive city of Homs.
Responding to the Red Cross appeal, White House spokesman Jay Carney said: "The reprehensible actions taken by the Assad regime, the brutal violence perpetrated by the Syrian leader against his own people has led us to this situation where humanitarian supplies are very scare, and therefore action needs to be taken.
"So we would certainly support the calls for those kinds of ceasefires."
US State Department spokesman Victoria Nuland said Washington wanted the violence to stop completely.
"If a pause is the best we can do, then we obviously want to get humanitarian aid and we want international organisations to be able to get humanitarian aid to those who are suffering from Assad's onslaught."
Asked about the possibility of arming the rebels, Ms Nuland said: "We don't believe that it makes sense to contribute now to the further militarisation of Syria.
"That said... if we can't get Assad to yield to the pressure that we are all bringing to bear, we may have to consider additional measures."
The Local Co-ordination Committees, a network of activist groups, said at least 45 people had died during a heavy bombardment of Homs on Tuesday and dozens more were killed when government forces attacked villages in Idlib province.
Violence was also reported in the suburbs of Damascus.
Syria bars most foreign journalists and the numbers of casualties cannot be confirmed.
Opposition groups say the army is reinforcing its presence around Homs in preparation for a ground assault that rights groups have warned could turn into a massacre.
But the BBC's Jim Muir, monitoring events from neighbouring Lebanon, says it is unclear if the bombardment is the precursor to a ground assault.
World and Arab leaders are due to meet in Tunisia on Friday to discuss Syria's future.
But Russia, a key ally of the regime, says it will not attend the "Friends of Syria" meeting because the Syrian government would not be represented.
Russia and China have faced Western and Arab criticism for blocking a UN Security Council resolution that would have backed an Arab League peace plan for Syria.
Mr Assad has been trying to quell unrest for several months.
Unarmed protesters are now being backed by rebel fighters who have defected from government forces and call themselves the Free Syrian Army.