Syria strongly condemned the presence of the Turkish and U.S. forces in Syria's northern city of Manbij, state news agency SANA reported Tuesday.

Syrian Foreign Ministry was quoted as saying that the presence is an "invasion" by the two powers that violates the sovereignty of Syria, adding that such moves aim to prolong and complicate the Syrian crisis.

The ministry said the Syrian army and people are determined to liberate all Syrian territories from any foreign presence to preserve the unity and sovereignty of the country.

It also urged the international community to "condemn this aggressive behavior of the U.S. and Turkey, which constitutes a flagrant violation of the principles and charters of the United Nations."

A day earlier, the Turkish and U.S. forces started conducting patrols on the outskirts of Manbij, which is under the control of the Manbij Military Council, an allied group with the Kurdish-led Syrian Democratic Forces.

This military presence came as part of a U.S.-Turkish joint understanding on the situation in Manbij, which included the need for the Kurdish People Protection Units (YPG) to withdraw from that city upon Turkey's request.

The Turkish forces will be patrolling the frontline between the Manbij council and the Turkish-backed Syrian rebels in the countryside of Manbij, which is close to the Turkish border, according to the Turkey-U.S. deal.

The agreement came after Turkey threatened to send its troops into Manbij, where 2,000 U.S. troops are stationed, like its operation to capture the formerly Kurdish-controlled Afrin enclave in northern Syria earlier this year.

Turkey does not want any presence of the Kurdish forces near its border, while the U.S. has for long supported the Kurdish forces in its fight against the militant group Islamic State.