DUBAI (Reuters) - Political infighting in Iran after Washington last year quit a nuclear deal between Iran and world powers forced Foreign Minister Mohammad Javad Zarif to announce his resignation, a close ally told Reuters on Tuesday.

“Zarif and President (Hassan) Rouhani have been under a huge amount of pressure from top officials since last May ... the U.S. exit intensified political infighting in Iran,” said Zarif’s ally, who asked not to be named.