Inspectors from the Organization for the Prohibition of Chemical Weapons were seeking on Tuesday to enter Douma, a suburb of Damascus, where the United States and Western allies say the Syrian government dropped chemical weapons.

Syria and its main backers, Iran and Russia, say claims of chemical weapons use were concocted by rebels, rescue workers and the West.

Syrian state media said on Tuesday that inspectors had entered Douma. The organization would not comment on those reports.

It’s the second time recently that the organization has been thrust into a geopolitical crisis — another high-profile case, the poisoning of a Russian former spy and his daughter in Britain, also drew attention to the group.