The father of a man killed in last week's London Bridge terror attack has launched a veiled attack on Boris Johnson for using the incident to call for tougher criminal sentencing.

Dave Merritt, father of 25-year-old Jack, said his son would be "livid" at "his death, and his life, being used to perpetuate an agenda of hate that he gave his everything fighting against".

"What Jack would want from this is for all of us to walk through the door he has booted down, in his black Doc Martens," Mr Merritt wrote in a memorial piece for The Guardian.

"That door opens up a world where we do not lock up and throw away the key.

"Where we do not give indeterminate sentences, or convict people on joint enterprise.

"Where we do not slash prison budgets, and where we focus on rehabilitation not revenge.

"Where we do not consistently undermine our public services, the lifeline of our nation.

"Jack believed in the inherent goodness of humanity, and felt a deep social responsibility to protect that."

Yesterday, Mr Merritt tweeted a plea in response to newspapers reporting that the prime minister was pledging a "blitz on freed jihads".

"Don't use my son's death, and his and his colleague's photos - to promote your vile propaganda," he wrote.

"Jack stood against everything you stand for - hatred, division, ignorance."

Mr Johnson had the comments put to him during an election campaign visit, and in response said "I feel as everybody does a huge amount of sympathy for the loss of Jack Merritt's family" - as well as relatives of Saskia Jones, 23, who was also killed by convicted terrorist Usman Khan on Friday.

"Be in no doubt - I've campaigned against early release and short sentences for many years," he insisted.

"It was in my manifesto in 2012 when I was mayor of London; I said it in August and it's in the Queen's Speech…

"I do think that unfortunately that is the problem we face - we have too many people who are released automatically on to our streets and we need to address that."