Syrian military forces have launched a fresh offensive on several towns in the north-western province of Idlib.
A BBC correspondent says troops have been firing artillery, mortars and anti-aircraft guns at Binnish and other towns near the city of Idlib.
Activists say dozens of people were killed across Syria, many of them in the besieged city of Homs.
As the crackdown continues, the European Union has imposed further sanctions on Syria.
They include:
a freeze on the European-held assets of the Syrian central bank
travel bans on seven close associates of President Bashar al-Assad
a ban on cargo flights from Syria into the EU
restrictions on the trade in gold and precious metals
UK Foreign Secretary William Hague welcomed the fresh sanctions.
"We will continue working closely with our EU partners to support the Arab League and its plan to end the violence in Syria and bring about a Syrian-led transition to a peaceful and more open political system," he said.
Qatar's Prime Minister, Sheikh Hamad bin Jassim al-Thani, said the international community should do "whatever necessary" to help the Syrian opposition, "including giving them weapons to defend themselves".
"I think they're right to defend themselves with weapons and I think we should help these people by all means," he added.
Tanks
The Local Co-ordination Committees (LCC), an activists' group which organises and documents protests, said that 89 people died in Homs, 64 of them in a single incident at a checkpoint - although there has been no independent verification of this.
The LCC also said 15 people died in Idlib area, nine in the Aleppo area, and several in the suburbs of Damascus.
The towns of Sarmin, Maarat al-Numan and Binnish were among the opposition-held areas of Idlib province reportedly hit by Syrian military attacks on Monday.
The BBC's Ian Pannell, who is in northern Syria, says residents of Binnish, which for the past week has been under the control of the Free Syrian Army and the Syrian Liberation Army, were woken by the sound of artillery bombardment.
Government troops are firing anti-aircraft weapons at the town, and also setting up mortar and infantry positions on the outskirts.
Our correspondent says the bombardment appears to be entirely random, hitting civilian areas rather than targeting rebel positions.
The Local Co-ordination Committees (LCC), an activists' group which organises and documents protests, said the towns of Sarmin and Saraqib, not far to the south of Binnish, also had been shelled.
The group said Maarat al-Numan outside Idlib, had been attacked, with several tanks entering the town from the south.
The French news agency AFP also reported shelling in the town of Qusayr, nine miles (15km) outside Homs.
'Extremely tense'
The International Committee of the Red Cross (ICRC) has continued efforts to move injured people, including two Western journalists, out of Baba Amr.
Reports on Monday evening said the Syrian Red Crescent had managed to regain access to the area but left later without the journalists.
British photographer Paul Conroy and French reporter Edith Bouvier were both wounded in an attack on Wednesday which claimed the lives of American journalist Marie Colvin and French photographer Remi Ochlik.
Poland's foreign ministry told the AFP news agency that its diplomats in Damascus were also attempting to retrieve the bodies of the dead journalists.
State television has meanwhile announced the results of a referendum on a new constitution, which was dismissed by opposition activists and the West as a sham.
The poll showed around 89% support for the proposal, the report said, on a turnout of just over 57%.
China earlier dismissed US criticism of its Syria policy as very arrogant.
A commentary in the Chinese Communist Party's official newspaper said that after the experience of Iraq, the US had no right to speak for the Arab people.
China's comments follow a blunt statement by US Secretary of State Hillary Clinton that the Chinese and Russian veto of a UN Security Council resolution on Syria was "despicable" while "people are being murdered".
