Syrian tanks have killed four people in the devastated city of Homs even as the UN and Arab League special envoy Kofi Annan prepared to visit the country for talks on humanitarian aid.
"Thirty tanks entered my neighbourhood at seven this morning and they are using their cannons to fire on houses," one resident of the Karm al-Zeitoun district told the news agency Reuters.
Activists with the Avaaz network reported that people are dying in the city because of a lack of food, water and medical aid.
One activist named as Abu Khaled said: “A small child called Zainab Alqisab died as a result of the blockade. She was sick and needed immediate medical treatment but the siege imposed on the neighbourhood prevented help arriving on time.”
The Local Coordination Committees claimed 20 people had died so far on Friday.
Meanwhile two Syrian generals and a colonel were reported to have defected to the opposition after a deputy oil minister announced his own resignation on YouTube on Thursday.
Burhan Ghalioun, the leader of the opposition Syrian National Council, rejected Annan's calls for dialogue ahead of his visit to the country, saying it would just give more time to the regime to continue the slaughter.
"These kind of comments are disappointing and do not give a lot of hope for people in Syria being massacred every day. It feels like we are watching the same movie being repeated over and over again," he told the Associated Press.
Elsewhere there were warnings of another large-scale massacre in the northern province of Idlib, where protesters have gathered in large numbers demanding the end of the regime.
Activists reported troop build ups in the region and a steady stream of refugees out of the city of Idlib in readiness for a crackdown, and there have been reports of clashes between opposition troops and the Syrian army in the town of Kafr Nabl.
Towns across the country saw a night of widespread protests, according to videos posted by the opposition.
Opposition figures vowed to carry out further large-scale protests of Friday to mark the anniversary of a 2004 massacre by government forces which killed about 30 Kurds in the north east of the country.
State media published photos of weapons including rockets and grenades which it said were seized in farms near to Hama.
It said the cache included 26 Magnum rifles and 105 pump-action shotguns, and alleged the weapons were smuggled in from Turkey.
The Local Coordination Committees said that at least 62 people died on Thursday, including 44 people who it said were executed in Homs.
The LCC added that 20 of those killed were from the same family.
The London-based Syrian Observatory for Human Rights said that 18 had died on Thursday.
According to the UN at least 8,000 people have died in Syria since the start of the uprising almost 12 months ago.