ANKARA - Turkey was not satisfied with a new proposal submitted by the United States on the issue of establishing a safe zone in northern Syria, Turkish Foreign Minister Mevlut Cavusoglu said on Wednesday.

"New US proposals are not satisfactory for us. We got the impression that they want to stall just like what happened with Manbij (deal)," Cavusoglu told reporters at a press conference, after talks between the American and Turkish delegations in capital Ankara.

"A deal on a safe zone has to be reached as soon as possible. Our patience has run out," he said, warning of a possible Turkish invasion in the east of the Euphrates in Syria.

His remarks came after the two countries have held talks since Monday to discuss Syria, including the possibility of setting up a safe zone along the border with Turkey, which aims at preventing clashes between Turkish and Kurdish forces.

The meetings came after Turkey advanced its military buildup on its border with Syria for a possible new incursion.

Cavusoglu said in a recent discussion that his American counterpart Mike Pompeo asked him to wait for a military operation and offered to send a delegation with new proposals for the safe zone.

The proposal has "new ideas on who will be included in the safe zone and joint patrols between soldiers," Cavusoglu said, but the offer failed short on the topics of the depth of the safe zone, the elimination of the People's Protection Units (YPG) forces, which Ankara sees as the Syrian branch of the Kurdistan Workers' Party (PKK) group, and the control of the safe zone.

The United States has provided extensive support to the YPG forces in Syria since the group has led the fight against the Islamic State (IS) in Syria.

The US proposal on the safe zone is a process similar to Manbij deal, whose phases will be extended overtime on a specified schedule, a Foreign Ministry official told Xinhua on condition of anonymity.

Therefore, Ankara regards this offer as an attempt to stall Turkey's operation into Syria, the official added.

The US proposal does not meet with the expectations of Turkey, as the new offer is far behind the 30-km-depth, which the US President Donald Trump expressed earlier, said the official.

Furthermore, the new offer does not anticipate an elimination of the YPG from the area Turkey has determined.

Ankara and Washington agreed on a roadmap on Manbij in June 2018, which involves the YPG's withdrawal from Manbij and the town's joint control by Turkish and US forces.

Despite Ankara's pressure, the US and Turkish soldiers have so far only conducted joint patrols on the outskirts of Manbij while the town remains under US and YPG control.

Ankara has often criticized Washington for much delay in the implementation of the roadmap on Manbij and expected the town to be clear of the YPG.

The United States and Turkey are committed to "accelerated and concrete progress" on the roadmap agreed upon for the northern Syrian town of Manbij, the US Embassy in Ankara said on Wednesday.

Parties "discussed detailed proposals to enhance Turkey's security along the Turkish border in northeast Syria," said the statement.

In January, Trump proposed the establishment of the safe zone as a solution to ease tensions between Turkey and the US-backed Kurdish militia.

This was the fifth meeting of a US-Turkey joint working group which aims to eliminate differences in Syria and to have progress on the issues of Manbij deal and a possible safe zone in northern Syria.

Turkey and the US exchanged several proposals but the parties could not narrow the main differences so far. Ankara wants to have full control of the safe zone after all the YPG forces are withdrawn and all their facilities are destroyed.

Turkey wants a 30-40 km depth of the safe zone under Turkish military control so that no YPG troops can attack the Turkish border.

However, Washington earlier proposed around 10 km-deep safe zone with no permanent deployment of Turkish troops.