Press TV - US National Security Adviser John Bolton has commented on the acting IAEA chief�s visit to Iran, making false accusations against Tehran with no evidence.

In a tweet on Saturday, the hawkish US official accused Iran of �concealing nuclear material and/or activities,� amid the visit by the acting chief of the agency, Cornel Feruta.

The American national security adviser also said that he is �eager to get a full report as soon as possible.�

The European Commission said Friday it was relying on the International Atomic Energy Agency in regard to Iran's nuclear activities.

An IAEA spokesman said on Friday that the acting chief of the agency was going to visit Iran to hold talks with high-level Iranian officials in Tehran on Sunday.

Commission spokeswoman Maja Kocijancic told a media briefing in the EU�s de facto capital Brussels that "our commitment to the nuclear deal depends on full compliance by Iran."

In a letter to the EU foreign policy chief Federica Mogherini on Thursday, Iranian Foreign Minister Mohammad Javad Zarif said Iran would begin unlimited nuclear research and development work from Friday, officially unleashing the third stage of its measured responses to Europe's lack of action in the face of Washington's violation of the nuclear deal.

Iranian President Hassan Rouhani first announced the decision to expand research and development (R&D) work beyond JCPOA limits on Tuesday. He gave the other side 60 more days to fulfill its