MP Tobias Ellwood was hailed a "hero" and commended for his bravery after he was pictured administering first aid to PC Keith Palmer, a casualty of Wednesday's terror attack in London.
Officers had commanded members of the public to stay well back in the aftermath of the atrocity, but Ellwood's friend of 20 years ,Conservative MP Adam Afriyie, told the BBC that the Foreign Office Minister immediately rushed forward to help the fatally wounded police officer.
Ellwood - a Conservative politician and former army officer - performed mouth-to-mouth resuscitation on Palmer, and attempted to apply pressure to the police officer's wound in New Palace Yard, Westminster.
PC Palmer had been stabbed by the attacker, who was later shot and killed by police.
Paramedics also fought to save his life and that of the attacker, on the ground of the courtyard in front of Parliament.
Four people, including PC Palmer and the assailant, died in the attack.
Speaking to The Sun, Ellwood said: "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."
The politician lost his own brother teacher Jonathan Ellwood in the Bali terror bombing in 2002, which claimed 200 lives.
Meanwhile, Acting Deputy Commissioner and head of counter-terrorism at the Metropolitan Police, Mark Rowley has said he thinks he is aware of who the attacker is, and that he was inspired by Islamist terrorism.
The attack happened in the capital at around 14.40 GMT on Wednesday, during which a lone assailant mowed down pedestrians on a pavement over Westminster Bridge, killing three and injuring 40.
After crashing the car into the railings, the attacker then ran towards parliament where he stabbed and killed PC Palmer.
The assailant was then shot dead by armed police officers.
The attacker's other victims have not yet been named.