John Brennan, the CIA director, has warned Donald Trump that scrapping the Iranian nuclear deal would be the "height of folly" and could lead to an arms race in the Middle East.

Mr Brennan, who will step down in January after four years as America's top spy, said it would be "disastrous" for the president-elect to follow through on his campaign pledge to terminate the accord.

"First of all for one administration to tear up an agreement that a previous administration had made would be almost unprecedented," he told the BBC, "and then it could lead to a weapons program inside of Iran that could lead other states in the region to embark on their own programs.