The fact-finding team on the ground was held up after Syrian and Russian officials said "there were still pending security issues to be worked out" before the inspectors could visit the area, the director-general of the OPCW in the The Hague, Ahmet Üzümcü, told members of the group's executive committee. This news comes despite assurances from both the Russian and Syrian governments that they would be taking responsibility for the teams' safety.
The Syrian Deputy Prime Minister has met several times with the inspectors since they arrived on Saturday, but the issue remains unresolved.
Earlier in the day, Russian Deputy Foreign Minister Sergei Ryabkov told reporters in Moscow that the OPCW inspectors had not been able to visit the site of the attack, in an area called Douma, because they lacked approval from the U.N. Department for Safety and Security, Russia media reported. The OPCW had been in "close contact" with that department to ensure the team's safety, Üzümcü said.
Russian military personnel visited the site last week. Syrian authorities declared Douma fully liberated after the last rebel fighters and their families left on Friday.
But, crucially, the OPCW wants to reach the area to interview witnesses to events as well as to take scientific samples. The Syrian government has instead offered to bring 22 witnesses to Damascus for the inspectors to interview there, Üzümcü said.
ABC News' Anastasia Butler contributed reporting from Moscow.