Demopnstrators outside the offices of the al-Qa’ida-linked Islamic State of Iraq and the Levant demanding they stop fighting with rebels in the Syrian city of Aleppo. Source: AFP

A broad coalition of moderates and Islamists opposed to President Bashar al-Assad is seeking to drive ISIL – which is accused of kidnapping, torturing and killing rival rebels and civilians – from its stronghold in the northern city of Raqa. The new front in Syria’s increasingly complex civil war opened less than three weeks away from a planned peace conference, for which the UN has started sending out invitations, excluding Assad’s ally Iran.

The Syrian Observatory for Human Rights said rebels in Raqa managed to free 50 Syrian prisoners held by the Sunni extremists, believed to be holding hundreds of prisoners, including foreign journalists.

Raqa is the only provincial capital lost by the regime since the conflict began in March 2011.

The city later fell into the hands of ISIL, the latest incarnation of al-Qa’ida’s Iraq affiliate, which joined the fight against the regime early last year.

The rebels initially welcomed the jihadists, but tensions mounted as ISIL was accused of imposing a reign of terror in areas where it operates.

Three powerful rebel alliances launched on Friday what activists called a second “revolution”, and have advanced quickly, expelling ISIL from checkpoints and bases across Aleppo, Idlib and Hama provinces. The Observatory said the main group besieging ISIL’s Raqa headquarters was Al-Nusra Front, which is also affiliated with al-Qa’ida but is seen as less extreme and has long competed with ISIL to represent the global terror network in Syria.

ISIL has struck back, including with a car bombing at a rebel checkpoint in Darkush, Idlib, that killed an unknown number of fighters on Monday, the Britain-based Observatory said. In Aleppo, a 16-year-old ISIL suicide attacker detonated himself at a rebel checkpoint, killing one opposition fighter and wounding others.

A key complaint among the rebels fighting ISIL is that the self-styled Islamic state sought hegemony over areas under its control, while activists and rights groups accused it of torturing and killing its rivals.

On Monday, the body of a decapitated child was found near ISIL’s headquarters in Kafranbel, Idlib, the Observatory said.

The Syrian conflict is estimated to have killed more than 130,000, and has forced millions more to flee their homes.

UN leader Ban Ki-moon started sending out invitations to the so-called Geneva 2 peace talks, but Assad’s key ally Iran was not on the first list, UN deputy spokesman Farhan Haq said.

Iran said it would only accept an offer to participate that respected its “honour”.

The decision may help pave the way for the opposition National Coalition, which has repeatedly stipulated Iran must not be invited, to participate. The Coalition was expected to discuss overnight whether to attend the talks, although a key group – the Syrian National Council – has already announced its boycott.

The 30 countries invited to the Geneva talks include Saudi Arabia, a major backer of the Syrian opposition, as well as Britain, China, France, Russia and the US – the five UN Security Council permanent members – and Syria’s neighbours such as Turkey, Iraq and Jordan.

US Secretary of State John Kerry and Russian Foreign Minister Sergei Lavrov will meet on Monday to decide Iran’s role in ending the war, said UN deputy spokesman Farhan Haq.

AFP THE AUSTRALIAN