Scores of people have been killed by an IS car bomb at a checkpoint outside al-Bab. Picture: AFP

As Iraqi and Coalition forces continue their attack on Mosul, the bomb ripped through the checkpoint controlled by Turkey-backed Syrian rebels in Sousian village, north of al-Bab, killing 60 and wounding many more.

On Thursday the rebels drove IS out of al-Bab, the terrorist group’s last stronghold in northwest Syria, after two months of fighting.

Dozens have been injured in the carbombing, by a vehicle packed with explosives, the Britain-based the Syrian Observatory for Human Rights says.

Scores of people have been killed by an IS car bomb at a checkpoint outside al-Bab. Picture: AFPSource:AFP

The blast devastated two adjacent rebel command posts and also seriously wounded a large number of fighters, the Observatory said.

Very graphic picture of the aftermath of the bombing were posted on social media.

Activist groups Aleppo Media Center and UK-based Syrian Observatory for Human Rights recorded the death toll at between 53 and 60 people.

They said IS are believed to be behind the attack.

Al-Bab, just 25km south of the Turkish border, was the last IS stronghold in the northern Syrian province of Aleppo.

Rebels launched an offensive to capture the town last year with the support of Turkish ground troops, artillery and air strikes.

Turkey sent troops into Syria last August in an operation it said targeted not only IS but also US-backed Kurdish fighters whom it regards as terrorists.

The battle for Al-Bab has been the bloodiest of the campaign with at least 69 Turkish soldiers killed there.

Turkish Defence Minister Fikri Isik said on Thursday that its rebel allies had “near complete control” of the town.

The battle for al-Bab has been the bloodiest of the campaign. Picture: AFPSource:AFP

The attack came as Iraqi forces on Friday gained control of most of Mosul’s airport on the city’s southwestern edge and all of a sprawling military base next to it, Iraqi officials said - key milestones in the first phase of the battle to rout Islamic State militants from the western part of Mosul.

According to the spokesman of the Joint Military Operation Command, Brig. Gen. Yahya Rasool, after a day of fierce fighting, most of the airport was under Iraqi forces’ control.

A federal police officer said fighting was still underway in a small northern section of the airport, with pockets of IS militants there.

Meanwhile, an Iraqi special forces official said his troops have retaken all of a sprawling military base adjacent to the airport. Both the federal police and special forces officials spoke on condition of anonymity in line with regulations. The multi-pronged assault onto the base and the airport started at sunrise on Thursday, closely supported by U.S.-led coalition troops on the ground and air strikes, as part of the battle to take the western half of Mosul that began six days ago.

Iraqi forces advance towards Mosul airport. Picture: AFPSource:AFP

Iraq’s special forces joined federal police and rapid response units in the push while the Popular Mobilization Forces - an umbrella group of government- sanctioned Shiite militias - secured the main roads west of Mosul, largely cutting the city off from IS-held territory in Syria.

Iraqi authorities declared Mosul’s eastern half “fully liberated” in January and afterwards largely paused operations to prepare for the fight for the city’s west.

The United Nations estimated that about 750,000 civilians are trapped in western Mosul. The initial numbers of displaced from western Mosul have been low, but Iraqi forces are yet to punch into the city’s dense urban neighbourhoods. The battle for western Mosul, the extremist group’s last major urban bastion in Iraq, is expected to be the most daunting yet, according to Iraqi and coalition officials.

The western half of the city is denser with older neighbourhoods and narrower streets that will likely complicate the already difficult urban combat ahead.

Displaced Iraqis flee their homes due to fighting between Iraqi special forces and Islamic State militants, on the western side of Mosul. Picture: APSource:AP