TEHRAN (AFP) ― Iran said talks Saturday with the U.N. atomic watchdog over allegations of Tehran’s past weapons work and additional safeguards were constructive and have been extended for another day.

The five-hour-long meeting came as the Islamic republic’s supreme leader, Ayatollah Ali Khamenei, demanded tolerance from critics of President Hassan Rouhani ahead of fresh talks with world powers.

Negotiations between Iran and the Vienna-based International Atomic Energy Agency are building on a framework deal agreed in November that requires Tehran to take six practical steps by Tuesday.

Chief inspector Tero Varjoranta and four experts are assessing the implementation of those measures, Iranian Atomic Energy Organization spokesman Behrouz Kamalvandi said.

The official IRNA news agency quoted Kamalvandi as saying that the talks were “good, constructive and are progressing.”

He said both side had agreed to continue the talks on Sunday, which are expected to include long-standing allegations of “possible military dimensions” to Iran’s past nuclear activities.

IAEA director general Yukiya Amano told AFP last month that time was now ripe to ask the “more difficult” questions.

How long this takes “very much depends on Iran. It can be quick or it can be long. It really depends on their cooperation,” Amano said.

Another issue to be discussed is access to the Parchin military facility, suspected of having been used for research pertaining to weapons development prior to 2003, and possibly since, according to the IAEA.

The November deal, struck after two years of on-off talks, was separate from a landmark agreement reached with world powers the same month that has placed temporary curbs on Iran’s nuclear activities.

Implementation of the IAEA deal began in December, when inspectors visited Arak, where the small unfinished heavy water reactor has been hit by delays.

The site is of international concern because Iran could theoretically extract weapons-grade plutonium from spent fuel if it also builds a reprocessing facility.

Iran says it will continue work there but its atomic chief Ali Akbar Salehi said this week the reactor could be modified to produce less plutonium to “allay the worries.”

The second step was to visit the Gachin uranium mine, which took place in late January.

Also required were information on future research reactors, identifying sites of new nuclear power plants, and clarification on Iranian statements regarding additional enrichment facilities and laser enrichment technology.

All six measures have been implemented.

The IAEA talks are running in parallel with efforts by the so-called P5+1 group of world powers seeking a comprehensive accord with Iran that would once and for all resolve the decade-long impasse over its nuclear work.

Full cooperation with the IAEA is a key demand of the P5+1 ― Britain, China, France, Russia, the United States and Germany.

Under the deal, Iran has stopped enriching uranium to medium levels and is converting its current stockpile into a form much more difficult to process into weapons-grade material.

In exchange, it has received limited relief from punishing sanctions which have hard hit its economy.

But the Rouhani government has faced increasing public opposition from establishment hardliners over the deal.