The International Committee of the Red Cross said Friday that it had been denied access to the stricken neighborhood of Bab Amr in the restive Syrian city of Homs, amid claims by activists that Syrian government forces had embarked on a campaign of revenge in which they were executing captives, looting property and burning homes.

Government forces continued the assault Saturday, pounding Homs and blocking aid to its residents, activists and aid workers said. In the southern city of Daraa, a suicide bombing killed two persons, the government news agency reported.

As many as 75 people were reportedly killed around the country as Syrians swarmed onto the streets to stage demonstrations calling on the international community to provide arms to the rebel Free Syrian Army, which retreated from Bab Amr on Thursday after running out of ammunition.

Among Friday’s casualties, according to the opposition Local Coordination Committees, were at least 14 men shot execution-style after being gathered together and blindfolded outside a commercial building in Bab Amr as the Red Cross relief mission was held at bay.

The withdrawal was a crushing defeat for the fledgling rebel army in a neighborhood that has emerged as a beacon of inspiration for the nearly year-long uprising against President Bashar al-Assad’s government.

Syrian troops swept into the enclave Thursday as the rebels fled, ending a 27-day siege but also raising concerns for the safety of the civilians left behind. The New York-based group Human Rights Watch said at least 700 people have been killed and thousands wounded during the government forces’ daily artillery bombardments.

The watchdog group released satellite imagery from Feb. 25 that it said showed the “widespread destruction” caused by the bombardments, with at least 640 buildings showing signs of direct hits and 950 craters visible on open land in and around the neighborhood.

The siege also left civilians without access to food, water, medical supplies or fuel at a time when snow is falling, prompting the U.N. Security Council on Thursday to issue a nonbinding call for “immediate” humanitarian access.

But the ICRC said that although Syrian authorities had promised Thursday that it would be allowed to deliver aid to civilians Friday, the agency was being denied permission to enter the neighborhood.

In a statement issued in Geneva, ICRC President Jakob Kellenberger described the situation as “unacceptable.” He said Red Cross workers were waiting in Homs with emergency supplies, including food, blankets and medicine, and would remain there in the hope that they would soon be able to deliver the aid.

“The humanitarian situation was very serious then, and it is worse now,” he said.

The claims of atrocities could not be verified because all communications with Bab Amr have been severed since Syrian troops launched their ground offensive Wednesday to retake the area. The citizen journalists who had kept the world informed by uploading videos, e-mailing reports and conducting interviews about conditions there have either been killed or captured or have fled, other activists say.

Mulham Jundi, a member of the umbrella Syrian National Council who is hiding out in another district of Homs, put the number of executed men at 25. Citing reports from family members who fled the area, he said the victims were ages 14 to 25 and had been taken from their homes and accused of supporting the Free Syrian Army before being lined up and shot.

“The regime is going inside every home and detaining all the males aged over 14,” he said. “They are stealing everything of value, and if they don’t find anything to steal, they are burning the house.”

Rupert Colville, a spokesman for the U.N. Office of the High Commissioner for Human Rights, told CNN that the office was aware of the reports. “It is very, very alarming,” he said.

But the scale of Friday’s protests suggested that the rout of the rebels in Bab Amr has served only to invigorate opposition to the Assad regime, which has escalated the levels of violence used to repress the unrest in recent months. In one of the worst incidents Friday, 13 people died when what appeared to be a mortar shell or rocket was fired into a demonstration in Rastan, a town in the province of Homs.

The slogan for this week’s protests, which have become a Friday routine since the uprising erupted March 15, was “Arm the Free Syrian Army,” signaling the growing appeal of the still disorganized and lightly armed insurgent movement.

Saudi Arabia and Qatar have expressed support for arming the opposition, but Western powers, including the United States, remain reluctant to funnel arms to a rebel army that has no clearly identifiable leadership in a region of profound strategic, sectarian and ethnic complexity.

At a European Union summit in Brussels, French President Nicolas Sarkozy said any military support would have to be approved by a U.N. Security Council resolution, something that seems unlikely given staunch Russian support for the regime.

Sarkozy also announced that France had closed its embassy in Damascus in a sign of outrage at what Assad's government is doing.

Separately, the 27-nation European Union called on Assad's army to halt its attacks on rebels and the “human rights abuses inflicted on the civilian population.” It urged further pressure on Damascus and told Brussels-based E.U. bureaucrats to prepare more European sanctions against Assad and his lieutenants.

Correspondent Edward Cody in Brussels contributed to this report.