Beirut (dpa) - Syrian government forces have entered the northern Kurdish-dominated town of Manbij, as part of a deal between the Kurdish fighters and Damascus to confront a Turkish incursion.

The Syrian Observatory for Human Rights reported that Syrian troops have entered the town, and footage showing people in Manbij welcoming the troops was broadcast on Syrian state television.

Russian state media cited the Russian Defence Ministry as saying that the Syrian army had established "full control over Manbij and nearby inhabited communities."

Backed by the United States, the Kurdish-led People's Protection Units (YPG) militia seized Manbij in the northern province of Aleppo from Islamic State in 2016.

US President Donald Trump announced a pullback from Kurdish areas near the border last week, a move that was widely believed to give a green-light for a long-planned Turkish invasion.

Turkey launched the offensive last week targeting the Syrian Democratic Forces (SDF) and the YPG, which Turkey considers to be linked to the outlawed Kurdistan Workers' Party (PKK) that is waging an insurgency on Turkish soil.

According to Kurdish sources, the United States had three main bases in the north, north-west and west of Manbij.

On Monday, Trump imposed a raft of sanctions and doubled tariffs on Turkey over Ankara's assault on north-east Syria.

The Syria offensive is "being carried out successfully," Turkish President Recep Tayyip Erdogan said Tuesday in Azerbaijan's capital, Baku.

"God willing, we will secure the area from Manbij to our border with Iraq in a short time, enabling 1 million Syrian refugees in the first phase - and then 2 million - to voluntarily return home," Erdogan added, without elaborating.

"We will continue with our struggle until we realize our targets," Erdogan said.

Two civilians were killed after cross-border fire hit Kiziltepe district in the Turkish border town of Mardin, the governor said Tuesday.

One Turkish soldier was also killed in mortar fire in Syria's Manbij region, state news agency Anadolu said.
Meanwhile, SDF fighters took control of the key border town Ras al-Ain overnight to Tuesday, two days after Turkish troops and allied rebels had captured it, the Observatory said.

Kurdish sources confirmed the attack and said they also took over the nearby village of Tal Helef, on the outskirts of Ras al-Ain.

However, sources close to the Turkish-backed rebel groups told dpa that fierce clashes are ongoing in Ras al-Ain.

The campaign has forced all international aid agencies to leave the area, Kurdish authorities said.

"The humanitarian situation facing our displaced people from the areas affected by the aggression has worsened," the statement said, adding that international organizations have withdrawn their staff from the autonomous areas.

Kurdish authorities appealed to the United Nations, Arab League and European Union countries "to intervene quickly and provide medical, logistical and humanitarian assistance."

The UN Office for the Coordination of Humanitarian Affairs (OCHA) said at least 100,000 people have fled escalating violence since the offensive began on Wednesday.