The head of the UN atomic watchdog will to go Tehran on Monday for meetings with senior Iranian officials aimed at improving cooperation on Iran's nuclear activities, the IAEA said.

The visit comes amid tensions between the US and its European allies over Washington's bid to maintain an arms embargo on Iran and reimpose UN sanctions dating back to 2006.

It will be the first visit to Iran by Rafael Mariano Grossi since he became director general of the International Atomic Energy Agency in December.

The IAEA said in a statement on Saturday that Grossi will address Iran's cooperation with the agency and in particular access for its inspectors to certain sites.

"My objective is that my meetings in Tehran will lead to concrete progress in addressing the outstanding questions that the agency has related to safeguards in Iran and, in particular, to resolve the issue of access," he said.

"I also hope to establish a fruitful and cooperative channel of direct dialogue with the Iranian Government which will be valuable now and in the future."

His visit takes place shortly before a September 1 meeting in Vienna of the joint commission on the landmark 2015 deal between Iran and global powers that aims to prevent Tehran from developing a nuclear bomb.

The US and European nations are at loggerheads after Washington began the process Thursday of activating a controversial mechanism aimed at restoring UN sanctions on Iran.

Britain, France and Germany rejected the move, saying it frustrated their efforts to salvage the 2015 accord that US President Donald Trump pulled out of two years ago.

Washington controversially maintains it has the right to force the reimposition of sanctions through the agreement's "snapback" mechanism despite its withdrawal.