The US State Department on Monday said it was working to respond to a senior Republican congressman who requested more information on why the US special envoy for Iran has been placed on leave.
Michael McCaul, who heads the influential House Foreign Affairs Committee, wrote to Secretary of State Antony Blinken after Robert Malley was placed on leave last month over what the Iran envoy said was a review of his security clearance.
Mr McCaul gave the State Department until July 11 to provide a “full and transparent accounting of the circumstances surrounding Special Envoy Malley’s clearance suspension”.
The suspension of a top US interlocutor comes at a crucial time, with Tehran edging ever closer to producing weapons-grade uranium.
State Department spokesman Matthew Miller told reporters on Monday that officials were working with Mr McCaul's office.
“We take our oversight obligations extremely seriously,” Mr Miller said. “We obviously got the letter from the chairman. We've been reviewing it and we will be engaging with his office on the matter.”
News outlet Semafor reported on Friday that the FBI had opened a probe into Mr Malley's handling of classified information.
The FBI declined to comment.
Mr Malley's leave of absence came as indirect discussions between Washington and Tehran picked up in recent months.
In May, US officials travelled to Oman, where they held indirect talks with Iranian authorities, according to Iran’s Ministry of Foreign Affairs spokesman.
