Asked repeatedly whether classified information had been shared he did not deny that it had.

He said: "We had a very, very successful meeting with the Foreign Minister of Russia. Our fight is against Isil.

"We had a great meeting, we are going to have great success over the coming years and we want to get as many as possible involved to fight terrorism. That's one of the beautiful things we have with Turkey."

His comments appeared to undermine previous statements by White House staff, who had denied classified information was shared with the Russians.

The Kremlin also issued a denial. Vladi­mir Putin’s spokesman, Dmitry Peskov, said: "This is another piece of nonsense."

According to the Washington Post at the May 10 meeting Mr Trump disclosed the city in Isil territory where information about the electronics plot had originated. That was reportedly "code word" information, a level above top secret, meaning the ally wanted it "compartmentalised" and not shared with third countries, or even parts of the US government.