Chemical weapons inspectors' security team fired on in Douma

A UN security team doing reconnaissance at the site of an attack in the Syrian town of Douma has come under gunfire, the head of the Organisation for the Prohibition of Chemical Weapons has said, further delaying the arrival of chemical weapons inspectors.

The OPCW director general, Ahmet Üzümcü , told a meeting at the organisation’s headquarters in The Hague on Wednesday that the security team had been forced to withdraw.

Üzümcü said that when a reconnaissance team arrived at one site, a large crowd gathered and the team withdrew. At a second site “the team came under small-arms fire and an explosive was detonated. The reconnaissance team returned to Damascus.”

The delay in the inspectors’ arrival, 10 days after the attack, will raise fresh concerns over the relevance of the OPCW investigation and possible evidence-tampering.

The efforts to investigate the attack, which has been blamed on Bashar al-Assad’s government and sparked a joint operation by the US, Britain and France to bomb chemical weapons facilities near Damascus, has been repeatedly delayed despite Syria’s claim to have established full control over Douma and the surrounding region.

OPCW investigators arrived in Damascus on Saturday, the same day as the bombings by the three western powers. The Syrian government said they were bound for Douma, just outside the Syrian capital, on Tuesday.

The source of the gunfire is unclear. The Syrian government said on Sunday it had “purified” Douma and the broader area of eastern Ghouta, which had been under siege for years and subjected to a number of chemical attacks, of “terrorists”.

Under the terms of a surrender deal negotiated after the chemical attack, Douma was to be emptied of heavy and medium weaponry, but those who stayed behind were allowed to keep light arms.

The OPCW does not usually comment on operational matters, such as details of when it would be able to visit a site, for security reasons.

The Syrian White Helmets has pinpointed the locations where the victims of the attack are buried for the inspectors, the rescue organisation’s head, Raed Saleh, said.

The OPCW team will seek evidence from soil samples, interviews with witnesses, blood, urine or tissue samples from victims and weapon parts. More than a week after the attack, however, hard evidence might be difficult to trace.

The attack in Douma killed at least 42 people, and western powers have said they have credible evidence that Assad’s forces carried out the attack. The city was the last holdout in eastern Ghouta, which surrendered after a two-month scorched-earth campaign by the Syrian and Russian forces that killed about 2,000 civilians.

Medics and aid officials told the Guardian that staff who treated victims of the attack were subjected to “extreme intimidation” if they spoke out.

The UN special envoy for Syria, Staffan de Mistura, said he was exploring whether the renewed focus on Syria could prompt a relaunch of the deadlocked UN peace talks in Geneva.

He said in a statement that he was holding talks with officials from Turkey, Iran and Russia following meetings last week with foreign ministers at the Arab League summit in Saudi Arabia.

The prospect for talks largely rests on whether the Syrian government delegation are put under pressure by Russia to engage with the process. The Syrian opposition delegation at the last round of talks in Geneva said it was willing to hold talks without preconditions, a means of stating that Assad would not have to stand down at the start of any transitional government.

The last serious exchanges over talks turned on the composition of a UN-supervised committee to oversee the process of devising a new constitution for Syria.