The U.N. nuclear watchdog said a site in Syria contained infrastructure consistent with a nuclear reactor, concluding that the country’s former regime led by Bashar Assad failed to declare nuclear material, facilities and activities required under international safeguards.

Inspectors of the International Atomic Energy Agency (IAEA) last month visited two sites, one in Deir el-Zour and a second location related to nuclear material identified by Syria.

The IAEA said observations at the Deir el-Zour site confirmed that recently uncovered cooling infrastructure was consistent with that of a nuclear reactor.

The agency said it would continue to monitor the activities at the site "as the excavation work progresses."

"Based on the information provided by Syria and the results of the agency's verification activities conducted at several locations in Syria, the agency is able to establish that the former Syrian authorities had failed to report nuclear material, facilities and activities," it said.