DAMASCUS, Feb. 24 (Xinhua) -- At least 73 people, mostly rebels, were killed on Friday when the Islamic State (IS) group carried out a suicide car bombing against a group of Turkish-backed rebels in Syria's al-Bab near the Turkish borders, activists said.

The IS bombing targeted a security compound of the rebels in the town of Susian behind the defense lines of the Turkey-backed rebels, some eight kilometers northwest of al-Bab, which was the largest IS-held city near the Turkish borders.

The bombing came as a retaliation against the Ankara-backed militants, who succeeded, along with the Turkish forces, to dislodge IS from al-Bab on Thursday.

The withdrawal of the IS from al-Bab came after 100 days of battles against the Turkish forces and allied Syrian rebels fighting in an operation called the Euphrates Shield.

The IS claimed it had killed 400 Turkish soldiers and rebel fighters.

For the Turks, capturing the northern part of the city cut the way in the face of the growing Kurdish influence in northern Syria, a red line drawn by Turkey.

The Syrian army succeeded recently to besiege al-Bab from its southern edge, a move to prevent IS fighters to withdraw toward other stronghold in the eastern province of Deir al-Zour, or the northern city of al-Raqqa, the de facto capital of the terror-designated group.

Observers said the attacks on al-Bab were coordinated between the Russians and the Turks.

Meanwhile, Turkish officials announced the liberation of al-Bab, expressing readiness to move toward the northern city of al-Raqqa, the de facto capital of IS in Syria.

The Turkish army also issued a statement on Friday, saying that al-Bab has been fully seized from terrorist control by Turkish forces and the Syrian rebels fighting under the campaign of the Euphrates Shield.

"As of February 24, 2017, full control has been established over all districts of Al-Bab," the military statement said, adding that "Work is still ongoing to clear the area of mines, IEDs and unexploded ordnances."

The announcement came hours after the deadly blast in the city.

The Syrian government has yet to comment on the Turkish forces' capture of al-Bab, but previously accused Ankara of encroaching upon the Syrian sovereignty.

Recently, Turkish President Recep Tayyip Erdogan vowed that the Turkish forces would continue their advance to Islamic State's Syrian capital, Raqqa, once they seize al-Bab.

"The ultimate goal is to cleanse a 5,000-square-kilometer area," Erdogan said.

According to Turkish estimates, the Turkish army now controls 1,925 square kilometers of territories in northern Syria.