A spokesman for the US State Department said that the United States opposes any military move that destabilizes the situation in Syria, amid an escalation of retaliatory attacks by Turkey and Kurdish armed factions on the Syrian border.

On the other hand, Russia called on Turkey to exercise restraint in its use of "excessive" military force in Syria and not to escalate tensions, Russian news agencies quoted a Russian envoy to Syria on Tuesday.

The comments came after Turkey said the Syrian Kurdish YPG militia had killed two people in mortar attacks from northern Syria on Monday, following Turkish air operations over the weekend and a bomb attack in Istanbul a week earlier.

A child and a teacher were killed and six wounded as a result of mortar shells falling on a border neighborhood in the Turkish province of Gaziantep. A senior security official said the Turkish armed forces responded by bombing targets in Syria with aircraft.

Turkish President Recep Tayyip Erdogan said the operations would not be limited to air strikes and might include ground forces. Turkey has carried out several large military operations targeting the People's Protection Units and the Islamic State in northern Syria in recent years.

A US State Department spokesman said that Washington had conveyed to Ankara its deep concern about the impact of the escalation on the goal of fighting ISIS.

"Turkey has been urged not to launch such operations, and just like our Syrian partners have been urged not to launch attacks or escalate," he added in emailed responses to questions.

The United States has allied itself with the Syrian Democratic Forces, led by the People's Protection Units, in the fight against the Islamic State group in Syria, causing a deep rift with NATO member Turkey.

* Revenge attacks

Turkish warplanes have already launched air strikes on Kurdish militia bases in Syria and Iraq on Sunday, destroying 89 targets of the Kurdistan Workers Party (PKK) and the People's Protection Units (YPG), which Ankara says is a wing of the PKK.

The Turkish Defense Ministry said in a statement that 184 militants were killed in operations on Sunday and Monday.
Turkey said the military operations that took place over the weekend were in response to a bomb attack in Istanbul a week ago that killed six people. Turkey pointed the finger at the Kurdish militants.

The PKK and the Syrian Democratic Forces (SDF) denied involvement in the November 13 bombing in a densely populated neighbourhood.

A spokesman for the Syrian Democratic Forces said that the Turkish attacks over the weekend destroyed grain silos, a power station and a hospital, killing 11 civilians, an SDF fighter and two guards. He added that the Syrian Democratic Forces would respond.

The PKK rebelled against the Turkish state in 1984, and more than 40,000 people died during the conflict. Turkey, the United States and the European Union classify the PKK as a terrorist organization
Source: Reuters