The U.N. nuclear watchdog policing Iran’s deal with major powers said on Wednesday that attempts to pressure it on inspections were “counter-productive and extremely harmful”, though it stopped short of naming those responsible, Reuters reported.

In a speech to staff on Wednesday, however, IAEA chief Yukiya Amano was blunt.

“If our credibility is thrown into question and, in particular, if attempts are made to micro-manage or put pressure on the agency in nuclear verification, that is counter-productive and extremely harmful,” he said, according to a text of the speech posted online by the IAEA.

He did not elaborate on the attempts or those behind them.

The IAEA is policing the restrictions placed on Iran’s nuclear activities under the deal, which also lifted international sanctions against Tehran.

“The IAEA is the only international organization that can verify the nuclear program of the DPRK,” said Amano, using the acronym of the country’s official name — the Democratic People’s Republic of Korea.