In a confidential report seen by news agencies on Friday, the IAEA said it cannot confirm that Iran hasn’t diverted nuclear material away from peaceful purposes, reported The Times of Israel. The IAEA “is not able to conclude that there has been no diversion of declared nuclear material from peaceful nuclear activities in Iran,” the report said, attributing the problem to Iran’s “lack of cooperation.” The IAEA said it is “increasingly concerned” about a uranium-enrichment plant at Isfahan that Iran declared to it last year but which it has not allowed agency inspectors access to. In its report, the agency said that it was “critical” for it to conduct “verification activities in Iran without further delay.”

The report stated, “The director general encourages Iran to consider technical and gradual measures by which conditions are achieved that allow for the return of agency inspectors to Iran.”

The IAEA “acknowledged that the military attacks on Iran’s nuclear facilities and sites created an unprecedented situation.” Still, the agency said the lack of cooperation raised “serious proliferation concern” that “needs to be rectified with the utmost urgency.”