TEHRAN: Iran said Monday it had taken "no decision" to delete footage from surveillance cameras installed at some of its atomic energy facilities by the UN nuclear watchdog the IAEA.

The issue is part of broader talks underway in Vienna aiming to salvage the 2015 Iran nuclear deal that has been hanging by a thread since former president Donald Trump withdrew the US from it three years ago.

"No decision has been taken on the deletion of the data" recorded by the IAEA cameras, said Iranian foreign ministry spokesman Saeed Khatibzadeh.

Tehran also denied the IAEA access to video recordings from monitoring equipment that the UN agency had installed at its sites to verify its compliance.

The Atomic Energy Organisation of Iran said the cameras would keep running, but that the withheld footage would be deleted if US sanctions were not lifted within three months.

This period was later extended by a month but expired on June 24. Since then the IAEA has insisted on the "vital importance" that Iran extend the period again and urged Tehran to tell it whether it intends to do so.

But Tehran's response has been slow in coming.

"I insist that no negative or positive decision regarding the cameras and the previous agreement with the agency has been taken," Khatibzadeh said on Monday.

The decision is the responsibility of Iran's Supreme National Security Council, which is not known to have held a meeting on the subject since June 24.