Syrian government forces mounted wide-scale attacks deep inside the country's most restive provinces on Wednesday, leaving at least 73 people - among them 18 babies - dead, according to opposition activists, dpa reported.
"This wide-scale operation follows a green light given by the Russians to the (Syrian) regime," Omar Idlibi, a spokesman for the opposition Local Coordination Committees, told dpa in Beirut.
"The number of casualties is on the rise. We cannot keep track of the figure, as there are many injured people who will die from their untreated critical wounds due to a lack of medical care and electricity outage," he added.
The onslaught against the dissident provinces of Homs and Daraa came a day after Russian Foreign Minister Sergei Lavrov met with Syrian President Bashar al-Assad in Damascus.
Homs, dubbed the "capital of the Syrian revolution," bore the brunt of Wednesday's crackdown, according to the opposition.
More than 20 buildings were flattened by the government forces' heavy shelling of the neighbourhood of Baba Amr in Homs, they said.
"This is a real war. All telephone lines are cut. People are dying from their wounds inside their homes. The situation is disastrous," said Idlibi the activist, as the sounds of exploding shells echoed in the background.
Rami Abdel Rahman, the head of the Syrian Observatory for Human Rights, said the deaths included three entire families.
Activists said the victims also included 18 premature newborns who died in a hospital due to the electricity cuts in Homs.
It is hard to independently verify such claims, as the Syrian authorities have barred most foreign media since the anti-government uprising started in March.
Homsi, the activist, appealed to the International Committee of the Red Cross (ICRC) to help save the injured in the province.
Saleh Dabbikeh, the ICRC spokesperson in Damascus, told dpa by phone that his committee was coordinating with the Syrian Red Crescent to send more medical supplies to Homs.
Elsewhere, Syrian military forces attacked areas in the southern province of Daraa, and clashed with army defectors, said the opposition.
"The onslaught is on the scale of the one the regime has been unleashing against Homs since the early hours (of Wednesday)," said Asil Abdullah of the Syrian Media Centre in Daraa.
Syrian state television, meanwhile, reported that a car bomb exploded in an area in Homs.
"A terrorist group detonated the car in the district of al- Bayyada, killing a number of civilians and security personnel," the broadcaster said.
The United Nations High Commissioner for Human Rights, Navi Pillay, called for immediate action to halt an escalation of violence in Syria.
"I am appalled by the Syrian government's wilful assault on Homs, and its use of artillery and other heavy weaponry in what appears to be indiscriminate attacks on civilian areas in the city," she said on Wednesday.
Russia, meanwhile, defended its sharply-criticized veto on a UN Security Council on Syria earlier in the week.
"What we stopped was the possibility to send military units, which would fight against government forces, and would occupy cities and villages," Russian Foreign Minister Sergei Lavrov said.
"It is absolutely outside any reasonable framework to create a UN resolution that assumes only government forces are firing on peaceful demonstrators. Half of the truth is worse than a lie," Interfax news agency quoted him as saying in Moscow.
In October, Russia, a key ally and arms supplier to Syria, vetoed a UN resolution condemning the Syrian government for its deadly crackdown on dissent.