As Turkish army and its rebel allies are pressing on a major offensive in al-Bab town in northern Syria, the advance risks confrontation with regime forces that are besieging the city from the south.

The Turkish forces and the rebels it's backing succeeded to capture a strategic hill in al-Bab last week and advanced towards the Islamic State (IS) stronghold from the north, east and west.

Turkish President Recep Tayyip Erdogan on Sunday said Turkish troops and Free Syrian Army (FSA) have entered the IS-held bastion town and its capture was now a "matter of time."

He vowed to move Manbij and Raqqa after al-Bab offensive in a bid to create a "terror-free zone" in northern Syria. The ultimate goal is to cleanse a 5,000-square-km area, he stated.

The move he was elaborating targets not only IS elements in Raqqa, but the Syrian Kurdish militia, which Turkey sees as offshoot of outlawed Kurdistan Workers' Party (PKK), in Manbij region.

Meanwhile, Syrian regime forces have been approaching towards al-Bab from the south since Feb. 6 and they were a few kilometers away from the town at the weekend.

Syrian regime forces advanced to Tadef town near al-Bab, which is located in Aleppo province's northeast, and destroyed IS stronghold, the Russian Defense Ministry said on Saturday.

The move brings the Syrian army to the demarcation line drawn to keep the rival forces apart over an agreement between Ankara and Moscow.

Turkey and Russia have signed a memorandum of understanding on Jan. 12 aiming to coordinate their military operations targeting IS militants in Syria.

The armies of two countries established "contact coordination line" aiming to avoid any confrontation between Turkish forces and Syrian regime forces backed by Russian air forces in northern Syria.

Tadef region is the demarcation line in south al-Bab between Syrian regimes with its allies, a Turkish official told Xinhua on condition of anonymity.

Despite the agreement between Ankara and Moscow that requires informing each side regarding their military operations in northern Syria, three Turkish soldiers were killed, 11 other injured when a Russian air strike "accidentally" hit their position in an attack targeting IS in al-Bab on Feb. 9.

Kremlin spokesman Dmitry Peskov said their air strikes were launched based on coordinates provided to Russia by the Turkish military, but the latter strongly denied Moscow's claim.

The Turkish army has been regularly sharing information with their Russian counterparts with regards to its Euphrates Shield operation in Syria in line with Jan. 12 agreement, the Turkish armed forces said on Feb. 10.

The Turkish military elements that were hit by Russian warplane were in the same location for about 10 days, said the Turkish army.

On Feb. 8, after a rocket was thrown from the region controlled by the Russian to the area where Turkish soldiers were located, they have transmitted again to the responsible personnel in Humeymim Operation Center and to the Russian Armed Forces Attaché in Ankara, said the army.

source: Xinhua