France’s foreign ministry has urged Turkey to end its assault on Kurdish fighters in northern Syria.

In a statement (in French) it said it was “worried about the continued worsening of the situation”.

On Saturday, Turkey began shelling the militia, which it says is linked to the banned Kurdistan Workers Party (PKK).

The fighters – the YPG militia based in Syria – have rejected Turkey’s demand to leave areas it has seized, saying Islamists would return if it left.

Turkey’s assault is a new thread in an already-complex conflict that has drawn in competing regional powers.

A statement on Syria’s state news agency also condemned Turkey’s intervention, calling it “outrageous violation of international law”.

France also called on the regime and its allies to stop their bombardments “across the whole of the country”.

France said priority should be given to implementing an agreement reached in Munich this week, and the fight against so-called Islamic State (IS) group.

Almost five years of civil war in Syria have led to the deaths of more than 250,000 people. About 13.5 million people have been displaced.

Attempts to broker a peace deal have repeatedly failed, but on Thursday, world leaders agreed to work towards a so-called cessation of hostilities in Syria within a week.

The US and Russian presidents agreed in a “frank and business-like” phone call to work more closely to achieve this, the Kremlin said on Sunday.

Russia, an ally of Syrian President Bashar al-Assad, has been carrying out airstrikes since September against what it terms “terrorists”.