♦ 150 IS fighter killed in Syria airstrikes: US

♦ Erdogan defiant amid US pressure to end Afrin push

Two dozen countries agreed Tuesday to push for sanctions against perpetrators of chemical attacks in Syria, with US Secretary of State Rex Tillerson saying Russia "ultimately bears responsibility" for such strikes.

Twenty-four nations approved a new "partnership against impunity" for the use of chemical weapons, just a day after reports they were used in an attack that sickened 21 people in rebel-held Eastern Ghouta, which Tillerson said was suspected to involve chlorine.

"Whoever conducted the attacks, Russia ultimately bears responsibility for the victims in East Ghouta and countless other Syrians targeted with chemical weapons since Russia became involved in Syria," Tillerson said after the international meeting in Paris, and ahead of further talks with ministers from several countries on ending the conflict.

"There is simply no denying that Russia, by shielding its Syrian ally, has breached its commitments to the US as a framework guarantor" overseeing the destruction of Syria's chemical weapons stockpiles, as agreed in September 2013, he added.

Despite its pledge to destroy such weapons, the Syrian regime has been repeatedly accused of staging chemical attacks, with the United Nations among those blaming it for an April 2017 sarin gas attack on the opposition-held village of Khan Sheikhun which left scores dead.

There have been at least 130 separate chemical weapons attacks in Syria since 2012, according to French estimates, with the Islamic State group also accused of using mustard gas in Syria and Iraq.

But the Kremlin yesterday accused Washington of trying to complicate international efforts to probe the use of chemical weapons in Syria and rejected accusations it was responsible for recent attacks.

Meanwhile, President Recep Tayyip Erdogan yesterday vowed to press Turkey's offensive against a Kurdish militia in Syria until "the last terrorist" was killed, as the US ramped up its concerns over the campaign.

Erdogan said the offensive was "continuing successfully", adding that Syrian opposition fighters and Turkish forces were "step by step taking control of Afrin". "Until the last terrorist is neutralised, this operation will continue," he vowed.

In another development, the US-led coalition said it has killed as many as 150 Islamic State fighters in an operation in the middle Euphrates River Valley in Syria.

According to a coalition statement on Tuesday, the air strikes took place Saturday near Al-Shafah, in Deir Ezzor province, on an IS headquarters where the jihadists appeared to have been "massing for movement."

"The precision strikes were a culmination of extensive intelligence preparation to confirm an ISIS headquarters and command and control center in an exclusively ISIS-occupied location in the contested middle Euphrates River Valley," the statement read.