"This step represents a blatantly unacceptable attack on the sovereignty of a brotherly Arab state... in violation of international law," the ministry said in a statement.

The statement came hours after Turkey launched an assault on Kurdish forces, unleashing air strikes and artillery fire along the border with war-torn Syria.

Cairo called on the international community to act against "this extremely dangerous development which threatens international peace and security".

It also warned against "any (Turkish) efforts to occupy Syrian territory" or to force a shift in the demographic makeup of northern Syria.

The ministry also urged the Arab League to hold an emergency meeting to discuss the assault.

The Arab League has also condemned Turkey's operation, warning it "could help Daesh (the Islamic State group) regain some of its force".

Relations between Ankara and Cairo deteriorated following the military ouster of Islamist former president Mohamed Morsi in 2013.

Morsi has since died in jail, and Turkey has become a safe haven for many Egyptian exiles, including former Muslim Brotherhood figures.

The strained ties have continued to sour with Egypt accusing Turkey in a joint statement on Tuesday with Cyprus and Greece of breaching international norms with its oil exploration in Mediterranean Sea.