WASHINGTON, Oct 20, 2021 (BSS/AFP) - The head of the UN nuclear watchdog agency expressed concern on Tuesday that Iran was holding up negotiations aimed at reviving the landmark accord that scales back its nuclear program in exchange for sanctions relief.

  International Atomic Energy Agency chief Raffael Grossi said he was still waiting for a "high level" discussion with Iranian officials in Tehran, as had been decided on in September.

  "We agreed that there would be a high level discussion, and this has not materialized yet," Grossi told reporters in Washington. "I hope that this will be done soon."

  Grossi said he is slated to return to Tehran for "a political discussion" with senior Iranian officials.

  "It could be the president, could be the foreign minister, I don't know. It is for them to say," Grossi added.

  On September 12, the IAEA negotiated with Iran a new compromise on monitoring Iran's nuclear program amid hopes for restarting talks in Vienna on bringing the 2015 deal with Tehran back to life.

  Grossi also lamented that UN inspectors still did not have access to a centrifuge components manufacturing unit at the Tesa complex located in Karaj, near Tehran, contrary to the September deal.

  "We have a problem because the cameras were affected by an act of sabotage that occurred there," Grossi said. "Something happened and our cameras were affected."

  In late September, Grossi warned that Iran must make its equipment and facilities accessible to monitors.

  Then-president Donald Trump in 2018 withdrew the United States from the deal negotiated by his predecessor Barack Obama, arguing that it did not address other concerns on Iran including its support for regional militants that target US allies Israel and Saudi Arabia.

  Since then Iran has stopped honoring some of its commitments under the accord.

  President Joe Biden's administration is working to restore the deal.