Barmah Research and Development Center in Damascus, Syria.
DigitalGlobe, via USA TODAY Network

The international chemical weapons watchdog that sent a fact-finding team to Syria said Monday that Syrian and Russian officials blocked efforts to reach the site where rebels claim government forces unleashed chemical weapons against civilians.

The Organization for the Prohibition of Chemical Weapons (OPCW) said the team arrived in Damascus on Saturday and met with government officials to work out a plan for deployment to Douma.

The Syrian and the Russian officials informed the team that "pending security issues" needed to be worked out before the group went to Douma, the organization's director general, Ahmet Üzümcü, told an emergency meeting of the group's executive council in The Hague, Netherlands.

"I hope that all necessary arrangements will be made through the UNDSS to allow the team to deploy to Douma as soon as possible," Üzümcü said, referring to the U.N. Department of Safety and Security.

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Russia initially blamed the delay on the United Nations, saying it had not provided the proper approvals. The UNDSS, however, said it had provided the necessary clearances.

Russia then blamed security issues on the heels of last week's joint, retaliatory missile strikes conducted by the U.S., Britain and France. The strikes targeted Syria's chemical weapons facilities.

Üzümcü said the Syrians had agreed to allow the fact-finding team to interview 22 witnesses who would be brought to Damascus. But he stressed the need for the team to investigate the site.

The rebel Syria Civil Defense Force says more than 40 people were killed and entire families were gassed to death in the attack, which drew global outrage. President Trump blasted "that animal" Syrian President Bashar Assad and said blame also fell on Russia and Iran for supporting his regime.

In addition to the missile strike in Syria, economic sanctions could be placed on Russia, the administration has said.

Syria and Russia have steadfastly denied the chemical weapons allegations. Both countries had invited the weapons watchdog group to send in the investigative team.

In London, Prime Minister Theresa May accused Syria, supported by Russia, of trying to conceal details of the attack in Douma. She also denied that Britain joined in military response simply at the behest of Trump. May said there was "clear evidence" Syria was behind the attack.

"No other group could have carried this out," May said.

Sherine Tadros, head of Amnesty International’s U.N. office in New York, urged Syria to allow the inspectors into Douma. 

“The OPCW team must be granted full and unfettered access to the site in Douma without further delay," Tadros said in a statement. "Their investigation is crucial in uncovering the exact circumstances behind the appalling images that united the world in horror this month."

A year ago, Syria was accused of using sarin gas in an attack in the town of Khan Shaykhun. An investigation by the U.N. and OPCW concluded the Syrian air force had used the gas in its attack, which killed almost 100.