BEIRUT: Several civilians were killed in an airstrike on an Islamic State held village in northern Syria, activists reported on Monday.

It was not immediately clear who is behind the airstrike southeast of the extremist group's de facto capital of Raqqa, and various activists groups reported different casualty tolls.

The Britain-based Syrian Observatory for Human Rights monitoring group said the strike hit the village of Akayrshi on Sunday night and that 12 women were killed. The activist-run Raqqa is Being Slaughtered Silently says the strike hit a convoy of farm workers, killing 22 people.

Both said the US-led coalition, which is waging war on IS, was most likely behind the airstrike.

The Islamic State group's own Aamaq news agency claimed 22 women were killed and eight wounded in a drone strike on a bus in Akayrshi, a village about 16 kilometers (10 miles) from Raqqa.

Kurdish-led Syrian forces backed by the US are advancing toward Raqqa after capturing several nearby towns and villages recently.

President Donald Trump's administration last week authorised the Pentagon to supply the force with heavy weapons for the Raqqa campaign, rankling Turkey, which says the fighters are affiliated with Kurdish insurgents operating within its own borders.

Russian President Vladimir Putin spoke on Monday about Moscow's own involvement with the Syrian Kurdish forces, assuring Turkey his country was not planning to arm them.

Putin lauded the Kurdish fighters as "one of the most efficient units" against IS and said Russia has "working contacts" with them.

Putin insisted that Moscow would not arm the Kurds because "they have other sources of obtaining the weapons."

Turkish President Recep Tayyip Erdogan during his recent visit to Russia has expressed concern over Russia's stance, but Putin said Monday "there is anything here to be concerned about."