Police have encouraged the public to attend events as normal after it was reported that an Armed Forces Day parade had been targeted by Islamic State (Isis).
An intended suicide bombing of a parade in south London on Saturday would have targeted soldiers from the same unit as murdered soldier Lee Rigby, according to The Sun.
The plot to explode a pressure-cooker bomb – to kill soldiers and bystanders on the route – was revealed after one of its leaders in Syria unwittingly recruited an undercover investigator from the newspaper to carry it out, the report said.
It is alleged that a figure in Isis, whom it named as Junaid Hussain from Birmingham, told the investigator: “It will be big. We will hit the kuffar (unbelievers) hard InshAllah. Hit their soldiers in their own land. InshAllah. Soldiers that served in Iraq and Afganistan will be present. Jump in the crowd and detonate the bomb.
“They think they can kill Muslims in Iraq and Afghanistan then come back to the UK and be safe. We’ll hit them hard InshAllah.”
The newspaper said the plot to bomb the parade in Merton, south-west London, was thwarted when it informed police and security services.
The parade was targeted because it was closest to the barracks in Woolwich, south east London, where Fusilier Rigby, 25, was murdered by Islamist extremists in 2013, the newspaper said.
Fusiliers from his regiment, serving Gurkhas and war veterans would be among the 250 marchers, it added.
A Scotland Yard spokesman said: “The police, together with our security partners, remain alert to terrorist threats that may manifest here or where individuals overseas may seek to direct or inspire others to commit attacks in and against the UK.
“It is always helpful when journalists share with us information, as The Sun did in this case, that could indicate terrorist or criminal activity.
“Attacks yesterday show the global nature of terrorism and the threat level in the UK from international terrorism remains unchanged at severe.
“While the UK threat level from international terrorism remains severe, we would like to reassure the public that we constantly review security plans for public events, taking into account specific intelligence and the wider threat.
“Our priority is the safety and security for all those attending or involved – the public are encouraged to continue with their plans to attend or take part in events as normal.
“We would also like to reiterate our longstanding advice to remain vigilant and alert. As ever, we would urge the public to get in touch to report anything suspicious by calling the confidential anti-terrorist hotline on 0800 789 321 or in an emergency by calling 999.”