Syria's opposition issued a cry for help on Sunday as regime forces pounded rebel bastions in Homs province and activists warned that hundreds of civilians were trapped with little food or water.
The opposition Syrian National Council (SNC), meeting in Istanbul, also demanded the deployment of armed peacekeepers a day after a UN observer mission said it was suspending operations because of the relentless bloodshed.
The mission chief, General Robert Mood, meanwhile, urged the warring parties to "allow women, children, the elderly and the injured to leave conflict zones, without any preconditions and ensure their safety."
"I call on the parties to take immediate action to ease the pain of Syrians trapped in the violence and the UN Supervision Mission in Syria (UNSMIS) stands ready to monitor their release, once the decision is taken," he said.
Violence cost at least another 37 lives on Sunday, taking the overall weekend death toll across the country to 108, according to the Britain-based Syrian Observatory for Human Rights.
Regime forces pounded rebel areas of the Old City of Homs and outlying towns, including Rastan and Talbisseh, in a bid to crush armed insurgents, the watchdog said, with deadly violence also reported in other parts of Syria.
A civilian was killed in the Homs city rebel bastion of Khalidiyeh, which was "being shelled and shot at by regime forces" while six others were killed in assaults on Rastan and Talbisseh, the Observatory said.
The situation in Rastan was also dire and most residents had fled to neighbouring villages, anti-regime activist Nidal al-Hakim told AFP via Skype.
Many people were "critically" wounded and there is a shortage of medication, while authorities have cut off electrical supplies and water from the besieged city, said Hakim.
"We couldn't bury our martyrs in the cemetery because... it is targeted by Assad's forces," he added.
Abu Bilal, another activist speaking from the Old City of Homs, said the regime assault on several parts of the central city was "suffocating."
"They are shelling us all the time. There's very little food and water, and we're running out of medication."
The Observatory has said that more than 1,000 families were stuck in the area, with dozens injured.
SNC chief Abdel Basset Sayda accused the regime of President Bashar al-Assad trying to commit new "atrocities" in Homs and Rastan. "The country is under a violent attack, especially Homs," Sayda told journalists in Istanbul.
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SNC spokeswoman Bassma Kodmani said the situation in Homs city was growing increasingly desperate, citing food and water shortages.
Towns, including Rastan, "are living through tragic hours and days. We are calling for immediate humanitarian intervention in favour of the people of Syria", she said.
Earlier the SNC issued a statement urging the United Nations to pressure Assad's regime using Chapter VII of the UN charter, which allows measures to be imposed on a country under penalty of sanctions or force.
The opposition specifically demanded that observers tasked with monitoring a UN-backed ceasefire -- that has been flouted daily since going into effect on April 12 - be armed.
A YouTube video uploaded on Sunday by activists showed clouds of black and grey smoke rising over buildings in the Old City of Homs.
The thump of shelling and gunfire ripped through the silence of what appeared to be a ghost town.
Another video showed widespread destruction in the Homs district of Jourat al-Shiah, including deserted streets and a shelled building on fire.
"We don't have any milk for the children, nor water, nor electricity," a mother of two whose house was destroyed says on the video.
"We are not scared. We don't want weapons or money. We just want a way to get our children out of here," she says.
The authenticity of the videos could not immediately be verified.
Home to rebel hideouts, Homs has been under intermittent attack by regime forces ever since its district of Baba Amr was relentlessly pounded for a month before being retaken by the regime early March.
Sunday's dead also included a 17-year-old boy "who was thrown from a fifth floor apartment by security forces after they raided his home in the (Damascus province) town of Daraya," the Observatory said citing activists.
UNSMIS suspended its operations two months into its three-month mandate on Saturday, blaming the intensifying violence threatening the 300-strong force.
Mood said the observers "will not conduct patrols and will stay in their locations until further notice," citing the force's inability to carry out its duties.
More than 14,400 people have died in the 16-month uprising against the regime of President Bashar al-Assad, according to the watchdog.