"Turkish forces and allied rebels in the Euphrates Shield campaign entered the western edge of the town and took control of a number of areas", the Britain-based Syrian Observatory for Human Rights said.
While Turkey and Russia were both very conciliatory over yesterday's botched airstrike in the Syrian city of al-Bab, in which a Russian warplane accidentally killed three Turkish soldiers and wounded 11, the two nations are offering very contradictory stories on what actually happened.
He said that the countries supporting the ISIL terrorist group have failed to take any military or political measure to protect al-Bab city or block the advances of the Syrian army.
After initial rapid progress, the campaign has been mired since December in the deadly fight for Al Bab.
The Turkish military said Turkey and Russian Federation were conducting a joint investigation into the bombing.
But despite that diplomacy, Turkey's military has refuted claims that it mistakenly told Russian jets to bomb the building where the three Turkish soldiers were positioned.
Earlier Saturday, the military released a statement and said a total of 223 Daesh terrorists were "neutralized" in northern Syria as part of Turkish-backed Operation Euphrates Shield over the past week.
The negotiations - brokered by Russia, Iran and Turkey - began last month with the aim of solidifying a broad ceasefire, in effect since late December. Capturing the city is of strategic importance to Turkey in order to prevent the Syrian Kurds taking it and unifying their own territories. Turkey claims to have killed at least 2,705 ISIL members and 344 Kurdish fighters.
Though small and out of the way, al-Bab is shaping up to be the weather vane for the rest of the conflict as the United Nations plans to convene Syria peace talks in Geneva on February 20.
Speaking with reporters, Turkish Deputy Premier Numan Kurtulmus said it was important that Russian President Vladimir Putin had expressed his condolences to Turkish counterpart Recep Tayyip Erdogan.
"The offensive operation resulted in the Syrian government forces' approach to the contact line coordinated with the Turkish side", it said.