At least four people have been killed and 15 injured after Syrian warships and tanks opened fired on the port city of Latakia in two residential districts, activists have said.
Sunday's deaths were reported as a military assault on Latakia extended into a second day.
On Saturday, armed forces killed at least five people and several were injured in the northern city.
In Damascus, activists reported a siege on Sa'aba, east of the capital, on Sunday, in an attempt to prevent funeral processions for two people who were killed on Saturday night.
Shooting and explosions were heard in another neighborhood, in Slaibeh on Saturday, according to the London-Based Syrian Observatory of Human Rights (SOHR) and the Local Co-ordination Committees (LCC).
Also on Saturday, scores of security agents and pro-government thugs, known as shabiha, entered the town of Qusair, near the border with Lebanon, and several nearby villages, arresting scores of residents, Rami Abdel Rahman, chief of the SOHR, said.
'Violence must end'
Canada said on Saturday that it had expanded sanctions on Syria to protest the government's brutal crackdown on protests.
The new sanctions include travel bans on four officials and freezing the assets of the state-run Commercial Bank of Syria, and Syriatel, the country's largest mobile phone company.
The US imposed sanctions on the two firms earlier in the week, and has joined European allies in sanctioning top officials close to Assad.
Canada's sanctions came after US President Barack Obama spoke with the leaders of Saudi Arabia and the UK and all three called for an immediate end to the Syrian government's crackdown on protests.
Obama and Saudi King Abdullah "expressed their shared, deep concerns about the Syrian government's use of violence against its citizens," the White House said in a statement.
"They agreed that the Syrian regime's brutal campaign of violence against the Syrian people must end immediately, and to continue close consultations about the situation in the days ahead."
Similar language was used in a statement after a separate Obama conversation with British Prime Minister David Cameron.
Tens of thousands of people rallied in cities across the country on Friday in protest against the government and at least 17 people were reported killed.
The protests have grown dramatically over the past five months, driven in part by anger over the government's bloody crackdown in which rights groups say at least 2,000 civilians have been killed across the country.
The government has justified its crackdown by saying it is dealing with terrorist gangs and criminals who are fomenting unrest.
A Latakia resident speaking to Al Jazeera on Saturday rejected the government's claims.
"There are no armed gangs here," he said. "We have been demonstrating peacefully for the last three months."
He said the army and security personnel together with regime thugs were shelling residential neighborhoods.
Syrian authorities have expelled most independent journalists since the five-month-old uprising against Assad began, making it difficult to verify reports from both sides.
PHOTO CAPTION
Syrian soldiers withdraw from the city of Hama after a 10-day military operation to quell pro-democracy protests.
Al-Jazeera