The Wall Street Journal reported Tuesday that guards at Iran's main nuclear facility, Natanz, physically harassed female International Atomic Energy Agency (IAEA) inspectors in several incidents since early June.

The incidents allegedly included inappropriate touching and orders to remove clothing, the report said, citing diplomats.

Asked to comment on the report, the IAEA noted in a statement "some incidents related to security checks of agency inspectors at one Iranian facility" in recent months.

"The agency immediately and firmly raised this issue with Iran to explain in very clear and unequivocal terms that such security-related incidents involving agency staff are unacceptable and must not happen again," it said.

The statement said there had been no further incidents after the IAEA and Iran exchanged messages on this matter.

"Security measures at the nuclear facilities in Iran are, reasonably, tightened" Iran's ambassador to the IAEA, Kazem Gharibabadi, wrote on Twitter late Tuesday.

"The IAEA inspectors have gradually come up with the new rules and regulations".

The Natanz nuclear facility was hit by an explosion in April, which Tehran has branded an act of "sabotage".

Separately, Tehran has restricted IAEA access since earlier this year, along with other steps to ramp up its nuclear activities since 2019 despite an accord with world powers, curbing Iran's programme in exchange for sanctions relief.

But the 2015 landmark agreement started to unravel when the US withdrew from it in 2018 and reimposed sanctions.

Talks to revive the deal with US participation are currently stalled.