Syrian opposition forces have launched a major offensive in a bid to seize control over the northwestern city of Idlib from regime forces.

Abu Yazid, a spokesman for Ahrar al-Sham - one of the country's largest opposition groups - told Al Jazeera that his forces were part of a coalition of seven armed factions involved in the ongoing "Operation to Free Idlib".

The "Fattah Army" coalition - including al-Nusra Front, Jund al-Aqsa, Jaish al-Sunna, Liwa al-Haqq, Ajnad al-Sham, and Faynad al-Sham - asked residents to remain indoors as the offensive began on Tuesday morning.

Yazid said that after two hours of heavy fighting with security forces that resulted in many casualties on both sides, the fighters managed to push into the city and take control of some parts of it.

"Many military targets were attacked and we have been succeeding...Fighting is still ongoing in Idlib city and neighboring areas," he added.

Opposition forces have controlled much of Idlib province since 2012. They are now trying to expand their control to the provincial capital, which President Bashar al-Assad's forces have so far managed to hold.

Syrian state TV on Tuesday quoted an unnamed military official as saying that regime forces were repelling "attempts by terrorists groups to infiltrate the outskirts" of Idlib.

PHOTO CAPTION

Islamic Ahrar al-Sham fighters fire a locally made weapon towards forces loyal to Syria's president Bashar Al-Assad on the frontline of Idlib city in northern Syria, where they announced a battle to liberate the city March 21, 2015.

Aljazeera