Theresa May rebuked Donald Trump over the Parsons Green Tube attack after he suggested those responsible had been “in the sights of Scotland Yard”.

Mrs May called the intervention by the US president “unhelpful”, as he appeared to claim Britain needed to be “tougher” and more “proactive” in the fight against terrorism.

The diplomatic row threatened to undermine the special relationship and intelligence sharing arrangements between the UK and US.

Mr Trump, not for the first time, also used the attack to justify his controversial proposed travel ban on people from some predominantly Muslim countries entering the US.

Following a backlash against his comments the president said he would be telephoning Mrs May “right now”.