The comments came as Turkish artillery kept up bombardment of Kurdish bases and other targets near Tal Rifaat and Kobani, two Syrian military sources told Reuters.

Moscow, which is allied with Damascus, also called on Türkiye to show restraint in its use of "excessive" military force in Syria and keep tension from escalating, Russian news agencies cited a Russian envoy to Syria as saying.

Türkiye said the Syrian Kurdish People's Protection Units (YPG) killed two people in mortar attacks from northern Syria on Monday, following Turkish air operations against the militia at the weekend and a deadly bomb attack in Istanbul a week earlier.

The YPG-led Syrian Democratic Forces (SDF) said 15 civilians and fighters were killed in Turkish strikes in recent days.

Turkish Defense Minister Hulusi Akar vowed to keep up operations against the militants, renewing calls for NATO ally Washington to stop backing forces in Syria that Ankara calls a wing of the outlawed Kurdistan Workers Party (PKK).

"We tell all our partners, notably the United States, at every level, that the YPG equals the PKK and persist with our demand that they halt every kind of support for terrorists," Akar told a parliamentary commission in a speech.

A child and a teacher were killed and six people were hurt on Monday when mortar bombs hit a border area in Türkiye’s Gaziantep province. Its armed forces responded with jets again hitting targets in Syria, a senior security official said.

President Tayyip Erdogan has said operations would not be limited to an air campaign and may involve ground forces. Türkiye has mounted several major military operations against the YPG and ISIS militants in northern Syria in recent years.

‘Serious concerns’

A US State Department spokesperson said Washington had communicated its serious concerns to Ankara about the impact of escalation on the goal of fighting ISIS.

"We have urged Türkiye against such operations, just as we have urged our Syrian partners against attacks or escalation," the spokesperson said in emailed responses to questions.

The United States has allied with the YPG-led SDF in the fight against ISIS in Syria, causing a deep rift with Türkiye.

Türkiye said its warplanes destroyed 89 targets in Syria and Iraq on Sunday, with 184 militants killed in operations targeting the YPG and PKK on Sunday and Monday.

Ankara said its weekend operation was retaliation for a bomb attack in an Istanbul last week that killed six people, and which authorities blamed on the militants. Nobody has claimed responsibility and the PKK and SDF have denied involvement.

The bombing evoked memories of violence ahead of tense 2015 elections, and could lead to another security-focused campaign for Erdogan, ahead of tight elections next June.

An SDF spokesman said the weekend Turkish strikes killed 11 civilians, an SDF fighter and two guards.

More than 40,000 people have been killed in fighting between the PKK and the Turkish state which began 1984. Türkiye, the United States and the European Union designate the PKK as a terrorist group.