BEIRUT: A misdirected air strike by the US-led coalition earlier this week killed 18 allied fighters battling the militant Islamic State group in northern Syria, the US military said on Thursday.

US Central Command said coalition aircraft were given the wrong coordinates by their partner forces, the predominantly-Kurdish Syrian Democratic Forces, for a strike intended to target IS militants south of their Tabqa stronghold, near the extremists’ de facto capital, Raqqa.

The strike hit an SDF position instead, killing 18. Central Command said the strike was launched on Tuesday.

Several nations have lent their air power to the US-led coalition to defeat the IS. It was not clear which air force was behind the strike.

The SDF acknowledged the strike on Thursday, saying a number of its fighters were killed and wounded.

The SDF-linked Hawar News Agency reported the group was holding funerals for 17 of its fighters in the border town of Tal al-Abyad, though it did not link them to the strike. An activist-run group, Raqqa is Being Slaughtered Silently, says three days of mourning have been declared for the town. The Britain-based Syrian Observatory for Human Rights said 25 SDF fighters were killed in the last two days of battle.

The SDF meanwhile announced the launch of a fourth phase of their campaign to capture Raqqa, a Euphrates River city that is home to 300,000 people.

The SDF, with US-led air and ground support, has surrounded Tabqa, some 40 kilometers south-west of Raqqa. They say they are working to clear IS militants out of Jalab Valley, north of Raqqa.

The SDF says it wants to isolate Raqqa before attacking it. Their closest position is less than 8 kilometers (5 miles) northeast of the city. But the countryside south of Raqqa is still under IS control. It is unclear how many stages are planned for the campaign.

Probe into chemical attack

The international chemical weapons watchdog is testing samples from the suspected nerve gas attack and could produce a report on the matter within three weeks, the British delegation to the commission said on Thursday.

The report comes one day after Russia vetoed a Western-backed UN Security Council resolution demanding a speedy probe into the Khan Sheikhoun attack.

The Organization for the Prohib­ition of Chemical Weapons has a standing fact-finding mission on Syria to investigate alleged chemical weapons attacks, but does not apportion blame. The OPCW’s executive council met on Thursday to discuss the attack on Khan Sheikhoun, in the northern rebel-held province of Idlib.

Britain’s delegation to the OPCW tweeted from the executive session that the “Fact Finding Mission is working to gather evidence” and has already started testing samples in a lab.

Russian Foreign Minister Sergey Lavrov said he expected the OPCW to conduct an extensive probe into the attack, and insisted the organisation visit both Khan Sheikhoun and the air base struck by U.S. missiles.

Published in Dawn, April 14th, 2017