BEIRUT—Food and water are running dangerously low in the besieged Syrian city of Homs, with frantic cries for help from residents amid the latest government shelling that has pounded rebel strongholds and killed at least 30 people, activists said.

This came as Secretary of State Hillary Rodham Clinton is trying to ramp up diplomatic efforts against President Bashar Assad’s regime on a trip to North Africa this week, as some countries begin to explore the possibility of arming Syria’s rebels.

Clinton is traveling to London on Wednesday for a conference on Somalia, but US officials will be using the international gathering to lay the groundwork for a major conference on Syria’s future taking place later this week in Tunisia. The trip comes as the Obama administration is opening the door slightly to international military assistance for Syria’s armed opposition.

In coordinated messages, the White House and State Department said on Tuesday they still hoped for a political solution. But faced with the daily onslaught by the Assad regime against Syrian civilians, officials dropped the administration’s previous strident opposition to arming anti-regime forces. It remained unclear, though, what, if any, role the US might play in providing such aid.

“We don’t want to take actions that would contribute to the further militarization of Syria because that could take the country down a dangerous path,” White House Press Secretary Jay Carney told reporters. “But we don’t rule out additional measures if the international community should wait too long and not take the kind of action that needs to be taken.”

Shells reportedly rained down on Tuesday on rebellious districts at a rate of 10 per minute at one point and the Red Cross called for a daily two-hour cease-fire so that it can deliver emergency aid to the wounded and sick.

“If they don’t die in the shelling, they will die of hunger,” activist and resident Omar Shaker told The Associated Press (AP) after hours of intense shelling concentrated on the rebel-held neighborhood of Baba Amr that the opposition has extolled as a symbol of their 11-month uprising against President Bashar Assad’s regime.

Another 33 people were killed in northern Syria’s mountainous Jabal al-Zawiya region when government forces raided a town in pursuit of regime opponents, raising Tuesday’s overall death toll to 63, activists said. The Local Coordination Committees, an opposition group, said more than 100 were killed on Tuesday, but the report could not immediately be confirmed by others.

Russia, one of Assad’s remaining allies, urged the United Nations to send a special envoy to Syria to help coordinate security issues and delivery of humanitarian assistance.

Assad’s forces showed no sign of easing their assault on Homs, Syria’s third-largest city, whose defiance has become an embarrassing counterpoint to the regime’s insistence that the opposition is mostly armed factions with limited public support.

The rebel defenses in Homs are believed to be bolstered by hundreds of military defectors, which have possibly complicated attempts by Syrian troops to stage an offensive.

On Monday, reinforcements of Syrian tanks and soldiers massed outside the city in what could be a prelude to a ground attack.

“Government troops have been unable to advance because of stiff resistance from defectors inside,” an activist in Homs told the AP on condition of anonymity, because of fears of government reprisal.

Another activist in Homs said the shelling started after repeated attempts by troops to storm the edges of Baba Amr, which the opposition has dubbed “Syria’s Misrata” after the Libyan city that refused to fall to withering government attacks last year.

One Homs resident, communicating with the AP by Internet chat, said many people are unable or too scared to go to the hospital for treatment. Some are bleeding to death at home.

“My cousin is a doctor and he said they’ve given up on treating serious wounds. The numbers are too many to cope with especially with so little supplies,” said the resident, who has provided reliable information in the past.

The resident, who lives just outside Baba Amr, said people in the neighborhood were surviving mostly on stocks of rice and canned corn and tuna, but those supplies also were running out fast after several weeks of attacks.

Some people go without bread for days, and when grocery stores and bakeries reopen during a lull in the shelling, long lines form quickly, the resident said, adding that shortages exist of all kinds of foodstuff and vegetables.

The Red Cross said it has been negotiating with Syrian authorities and members of the opposition to agree a temporary cease-fire so emergency aid can reach beleaguered parts of the country.

“The current situation requires an immediate decision to implement a humanitarian pause in the fighting,” said Jakob Kellenberger, the president of the Geneva-based International Committee of the Red Cross.

“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 the cease-fire should last at least two hours daily, so that Red Cross staff and Syrian Arab Red Crescent volunteers have enough time to deliver aid and evacuate the wounded.

Beatrice Megevand-Roggo, the ICRC’s head of operations for the Middle East, described Homs as “sort of a ghost city,” adding that other parts of Syria also were badly affected by the fighting.

White House spokesman Jay Carney backed a Red Cross call for a daily cease-fire in Syria in order to deliver humanitarian aid.

“The reprehensible actions perpetrated by the Syrian regime, the brutal violence perpetrated by the Syrian leader against his own people, has led us to this situation where basic supplies, humanitarian supplies are very scarce and therefore action needs to be taken,” Carney said.

US State Department spokesman Victoria Nuland said Washington was focused on “increasing the international isolation and the international pressure on the Assad regime to stop the violence altogether, so that we can move on to a democratic transition.”

In the northern province of Aleppo, the government said a Syrian businessman, Mahmoud Ramadan, was shot to death in front of his home in what appeared to be the latest in a series of targeted killings. The attacks, which include the slaying of an Aleppo city council member on Saturday, suggest that rebel factions are increasing turning to arms to strike back at members of Assad’s ruling system.

Residents and activists say a monthslong siege and stepped up attacks on Baba Amr recently have left the district without enough food, water, medicine and electricity.

“They bombed all the water tanks on the roofs of buildings. There’s no water. Some people have gone without bread for days,” said Shaker, who estimated the shells fell at a rate of about 10 per minute at some points in the attack. More than 200 people were wounded, he said, adding that two children were among the dead.

(AP)