Rob Malley , the US special envoy on Iran, has been placed on leave without pay, after his security clearance was suspended earlier this year amid an investigation into his handling of classified material, multiple sources told CNN on Thursday. A US official said that Malley’s clearance was suspended amid a State Department diplomatic security investigation into the possible mishandling of classified information. Another source familiar with the matter said he was placed on unpaid leave on Thursday afternoon. “I have been informed that my security clearance is under review. I have not been provided any further information, but I expect the investigation to be resolved favorably and soon. In the meantime, I am on leave,” Malley told CNN . US State Department spokesperson Matthew Miller also confirmed that Malley is on leave, adding that Abram Paley is filling in on an acting basis. "Rob Malley is on leave and Abram Paley is serving as acting Special Envoy for Iran and leading the Department's work in this area," Miller told Reuters in an email. Malley was appointed special envoy for Iran in January of 2021 and had led the Biden administration's unsuccessful effort to revive the 2015 nuclear deal from which then-US President Donald Trump withdrew in 2018. Talks between Iran and world powers on reviving the 2015 Iran nuclear deal have been stalled since September . At that time, Iran submitted a response to a European Union proposal to revive the deal. A senior Biden administration official said the Iranian response "is not at all encouraging.” A US official later said that the efforts to revive the 2015 Iran nuclear deal have “hit a wall” because of Iran's insistence on the closure of the UN nuclear watchdog's investigations. Related articles: GOP lawmakers probe Kamala Harris adviser's Iran ties Robert Malley had classified docs in private email account, phone Biden's former Iran envoy to teach at Yale Just whose side is America really on? Recent reports indicated that the US and Iran were close to an agreement on Iran’s nuclear program. However, US Secretary of State Antony Blinken this week denied that an agreement had been reached between the Biden administration and the Iranian government on Iran's nuclear program. "There is no agreement in the offing, even as we continue to be willing to explore diplomatic paths," Blinken said.