World Bulletin/News Desk

ISIL insurgents have seized several towns and villages from rival groups in the Syrian province of Aleppo, opening the way for further westward advances, an organisation monitoring the war in Syria said on Wednesday.

Already in control of large areas of northern and eastern Syria, ISIL's latest gains include the towns of Turkmen Bareh and Akhtarin, 50 km (30 miles) northeast of Aleppo, the Syrian Observatory for Human Rights, which is based in Britain, reported.

"We're about to lose Aleppo and no one cares," Hussam Almarie, a Free Syria Army (FSA) spokesman, told The Wall Street Journal. "We won't be able to recover the revolution if this happens. And we'll lose the moderates in Syria."

ISIL's advance in Syria has accelerated since the group seized control of the Iraqi city of Mosul in June.

Diplomats and rebels said the Syrian government, which is fighting rebels across the country, launched attacks on towns run by the group only after its militants advanced into neighbouring Iraq and seized a third of its territories.

ISIL is tightening its grip over areas of Syria under its control, including the city of Raqqa on the Euphrates river. Raqqa has become the group's Syrian power base.

The Observatory, which uses a network of monitors, reported battles between ISIL fighters and Syrian government forces near a Raqqa military airport, the government's last remaining position in the area.

The Observatory also reported two more killings by ISIL in Deir al-Zor overnight, bringing to 27 the number of people executed by the group in recent days as it tightens it grip over the eastern province.

The advance in northeast Aleppo province is part of a wider offensive to seize a belt of territory near the border with Turkey.

A Twitter feed reporting events in Akhtarin said two people had been killed while "resisting" ISIL's advance, including a 16-year-old boy. There was no way to verify the report.

The Observatory said it expected ISIL's next targets to be the towns of Azaz and Marea, a town a few kilometers to the west that is considered a stronghold of the ISIL as well as Azaz, a town located next to the Bab al-Salama border crossing with Syria. 

The militants also took a string of nearby villages over which they had been fighting, including Masoudiyeh, Dabiq and Ghouz.

The capture of Akhtarin has strategic significance as the town is "the gate to the northern countryside of Aleppo," said a local rebel commander.

Syrian Observatory for Human Rights said many fighters on both sides were killed.

To date, the Assad regime has been content with allowing the ISIL to weaken the FSA, though Syrian forces did engage militants in large-scale clashes in June. Western officials tell the Journal that the regime may wait until Aleppo falls before turning its full attention to the ISIL militants.

Aleppo was Syria's biggest city prior to the start of the anti-Assad uprising, with a population of three million. The months of fighting have taken their toll, and reduced the population to an estimated 300,000.

Syria's conflict began as a popular uprising against Assad's rule, but turned into an insurgency after government forces violently cracked down on demonstrators. It has since deteriorated into a civil war with sectarian overtones. Over 200,000 people have been killed in Syria in over three years of fighting, activists say.