Tobias Ellwood, whose brief includes anti-terrorism, performed mouth-to-mouth resuscitation on the officer in New Palace Yard within the grounds of Parliament.

The Tory MP and former army officer also tried to stem the flow of blood from the injured police officer, who has been named as PC Keith Paimer, working with emergency services to try to save the officer’s life.

He was photographed with a bloodied face after he was among those who tried to save the officer, who later died.

The politician, whose brother was killed in the 2002 Bali bomb attacks, told The Sun: “I tried to stem the flow of blood and give mouth to mouth while waiting for the medics to arrive but I think he had lost too much blood.

“He had multiple wounds, under the arm and in the back.”

The officer had been stabbed by a suspected terrorist, who moments earlier had driven a car into a number of pedestrians on Westminster Bridge.

Eyewitness Hugh Dickinson, a 21-year-old student from High Wycombe, posted a picture of the minister on Twitter, showing him with a bloodied face but saying “he looked to be fine”.

Mr Dickinson said: “He had blood on his forehead as you can see but he wasn’t bleeding profusely.”

The Bournemouth East MP is a Foreign Office Minister, with the Middle East, Africa and counter terrorism listed among the areas within his brief.

Labour leader Jeremy Corbyn was among those to heap praise on Mr Ellwood, saying: “Our thanks and gratitude go to the police and emergency services who responded so bravely, and to those – including the MP Tobias Ellwood – who went to the aid of the injured and dying.”