BEIRUT (AP) ― Syrian troops backed by tanks and helicopter gunships swept into another northwestern city early Friday, just days after laying siege to it, activists said. Big demonstrations were expected nationwide as the Syrian people pressed on with the uprising to oust President Bashar Assad.

Syria-based rights activist Mustafa Osso said large numbers of soldiers entered Maaret al-Numan. It was not immediately clear whether there were any casualties in the operation.

Many of the residents of Maaret al-Numan, a town of 100,000 on the highway linking Damascus with Syria’s largest city, Aleppo, have fled after Syrian forces swept through the northwestern province of Idlib last week near the Turkish border.

Omar Idilbi of the Local Coordination Committees, a group that documents anti-government protests, said troops are in full control of the town.

Since anti-government protests erupted in mid-March, inspired by democratic revolutions in autocrat-ruled Tunisia and Egypt, Assad has unleashed the military in region after region to crush street demonstrations. Human rights activists say more than 1,400 Syrians have been killed and 10,000 have been detained.

The operation in Maaret al-Numan coincided with opposition calls for protests Friday throughout the country naming it “The Day of Saleh al-Ali.” Al-Ali was an Alawite leader who led an uprising against French colonial rule in the 20th century.

The opposition has been giving a name for every Friday since the uprising began 13 weeks ago but using the name of an Alawite leader was designed to show Assad’s opponents were not rising up over secular concerns.

The Assad regime is dominated by the Alawite minority, an offshoot of Shiite Islam, but the country is overwhelmingly Sunni Muslim.

Alawite dominance has bred resentment, which Assad has worked to tamp down by pushing a strictly secular identity in Syria. But the president now appears to be relying heavily on his Alawite power base, beginning with highly placed Assad relatives, to crush the resistance.

Osso, the rights activists, said troops are now massing around the town of Khan Sheikhon, south of Maaret al-Numan. Earlier this month, any army forces were attacked by gunmen in the area. Two government tanks were damaged in the melee, the activists said.