Iran on Tuesday shrugged off comments by the UN atomic watchdog chief that Tehran's controversial nuclear drive is "worrying," insisting that such concerns can be resolved in "technical-legal" talks.

"If the (International Atomic Energy) Agency takes a rational approach in the talks an agreement is reachable ... (even) quickly," Iranian foreign ministry spokesman Ramin Mehmanparast said in his weekly press briefing.

"If there are worries they can be resolved in technical-legal talks," he added.

IAEA chief Yukio Amano's comments came after the agency said last Friday it remained "unable" to say all Iranian activities were peaceful and that Tehran had completed installation at its Fordo site, allowing it to significantly ramp up production.

"The situation is worrying but it is important to continue to seek a diplomatic solution," Amano told reporters after talks with French President Francois Hollande on Monday.

The IAEA and Iran have agreed to hold another round of talks on 13 December in Tehran.

Mehmanparast also repeated Iran's denial it is sanitising a suspect military base where the UN atomic watchdog wants to probe evidence of possible weapons research.

Amano said in Baghdad earlier this month that efforts to dismantle traces of possible weapons research at the Parchin site near Tehran were "ongoing."

"It is not possible to clean up nuclear activities and (nuclear) traces will remain," Mehmanparast said. "It is not appropriate for the director of the Agency to make remarks which the experts consider non-technical and not legal."

The IAEA wants Iran to grant it access to Parchin, which it visited twice in 2005 but wants to examine again.

Since the summer, some buildings at the base have been covered in massive tarpaulins to prevent surveillance by Western satellites.

The UN Security Council has passed four rounds of sanctions against Iran's disputed nuclear drive, and the IAEA's board of governors passed a resolution in September again calling on Iran to prove its programme has no military dimension.