Syrian troops pushed ahead with a new assault on the northern region of Idlib on Saturday, shelling one of the centres of the uprising against President Bashar Assad’s rule and sending families fleeing for safety as armed rebels tried to fend off the attack. Thick black smoke billowed into the sky.

The military operation has raised fears that the regime is planning a new all-out offensive in Idlib like the bloody siege last month that captured a restive part of the city of Homs, further south. While the fighting raged, U.N. envoy Kofi Annan met with Mr. Assad in Damascus during a high-profile international mission to mediate an end to the country’s yearlong conflict.

The state-run news agency SANA reported that talks between Mr. Assad and Mr. Annan were “positive” but there were no further details on the meeting.

In the town of Idlib, a number of families fled, clutching their belongings, according to an Associated Press team in the town, the main centre of the northern region. A group of women and children huddled with blankets in a room of one building.

Armed opposition fighters dashed through the streets, taking cover behind the corners of buildings in clashes with the troops. Wounded fighters were pulled into trucks to be sped to clinics for treatment. A group of men used shovels to destroy speed bumps along one street to allow ambulances and other rescue vehicles to drive faster.

Military reinforcements have been pouring into Idlib this week, including dozens of tanks and armoured personnel carriers, activists said, reporting that dozens have been killed in the area in recent days. Their casualty reports could not be independently confirmed. The moves suggested the regime was now turning its focus on Idlib after recapturing the rebel-held district of Baba Amr in the central city of Homs, in a month-long assault that reportedly killed hundreds and devastated the district.

The Homs bloodshed further fuelled calls among Arab countries and the West for action to stop the crisis, which many fear is moving closer to civil war as the opposition turns more to armed resistance. The U.N. estimates that more than 7,500 people have been killed since Syria launched its crackdown on the uprising, which began a year ago as peaceful protests against Assad. Activists put the toll at more than 8,000.

Russian Foreign Minister Sergey Lavrov sought to defend his country’s stance on the crisis before Arab leaders, angered by Moscow’s blocking of international pressure on Syria’s President to step down. Last month, just as the Homs offensive was heating up, Russia and China vetoed a draft U.N. Security Council resolution that would have supported an Arab League peace plan calling on Mr. Assad to hand over his powers.

That brought accusations that Russia, a longtime Assad ally, was giving Mr. Assad diplomatic cover to intensify his crackdown.

“We are not protecting any regimes,” Mr. Lavrov insisted at a heated session of the Arab League in Cairo on Saturday. “We are protecting international law... We are not looking for a special prize or geopolitical interest here.”

“If we agree to this, then we shall not really engage in discussing who is to blame” for the bloodshed, he said. “This could be done later by authority or international structure empowered to do this.”

Speaking after him, Qatar’s Prime Minister sharply criticised Mr. Lavrov’s remarks. “There is systematic genocide by the Syrian government,” Sheik Hamad bin Jassem Al Thani said, adding that Arabs are not looking for a ceasefire anymore after “genocide” and “systematic killings” of Syrians.

Mr. Annan’s visit to Damascus marks a new international push for peace nearly a year after protesters took to the streets to demand Assad’s ouster, inspired by Arab Spring uprisings in Tunisia and Egypt. Since then, the regime has dispatched snipers, tanks and civilian gunmen to crush dissent. As the death toll mounted, protests have spread, and some have taken up arms to defend themselves and attack government forces.

More In: International | News