The UK government’s adviser on political violence said the growth of a “toxic, dangerous environment” in public life increased the risk of there being an assassination attempt on a British politician, as he called on the home secretary to launch an investigation into the intimidation of candidates in the election. John Woodcock wrote to Yvette Cooper on Friday expressing his concern that a series of incidents in the election campaign could have been a “concerted campaign by extremists” that “underlined the gravity of the threat to our democracy”. In an interview with the Guardian on Sunday, Woodcock, who has the title Lord Walney, said the apparent attempted murder of Donald Trump was “a vivid reminder of the vulnerability of all politicians”. He added: “We have seen the growth in the UK of US-style politics of aggressive confrontation and intimidation which is unfortunately, exactly the toxic environment that could lead to another assassination attempt on a UK politician, of which we have already tragically seen a number in recent years.” Many political candidates and their staff suffered threats and intimidation in the run-up to the election. Several of those targeted were female Labour candidates standing in seats where there was a strong opposition to the party’s stance on the war in Gaza. Woodcock said he believed intimidation was increasingly being used as “a core electoral strategy to try to either get candidates defeated or bully candidates into submission”. He added that there was a particular pattern of abuse “created by aggressive pro-Palestine activists”. The peer called on Cooper and the security minister, Dan Jarvis, to commission a short inquiry to establish whether groups in different constituencies were working together before the 4 July general election. In his letter he said it should document what he termed the “dark underbelly” of abuse. He told the Guardian: “The stories coming back from constituencies, from election campaigns are horrific. I think our frontline politicians were shaken before this and they have come back from the campaign determined to do something about it. And the question is now what measures will be effective and how you create the atmosphere for a change of culture.” Woodcock, who was a Labour MP before becoming a cross-bench peer, was appointed by Boris Johnson’s government as an independent adviser on political violence and disruption. The findings of his review on the issue were published 24 hours before the election was called. Titled Protecting Our Democracy from Coercion, his report was condemned by protest groups, including Greenpeace and Just Stop Oil. They said its proposals, which included a review of undercover surveillance of activists and making protest organisers pay towards policing, would “weaken democracy”. In his letter to Cooper, Woodcock said there had been a “concerted campaign by extremists to create a hostile atmosphere for MPs within their constituencies to compel them to cave into political demands”. He also wrote that the “conduct of the election campaign in many communities has underlined the gravity of the threat to our democracy” from the abuse and intimidation of politicians. Woodcock said on Sunday he wanted the home secretary to “call an urgent review of the environment around Whitehall” where “there can be clear points of vulnerability” for MPs – as well as better protections at MP’s offices. He said there was an urgent need to address the risk to politicians. “It’s a really toxic, dangerous environment. And we have to keep reminding ourselves that we’re not talking in theoretical terms. We are blessed to have the sister of Jo Cox in parliament today, but she started her political career in the aftermath of her sister being murdered; David Amess was assassinated. “The threat is real and thankfully there has been a big increase in the amount of protection that is offered to MPs, but unless we can do more to address the culture that is driving this there will always be an element of mortal risk to our politicians because the whole of our democracy is based on connection with the public and MPs and councillors would never have it any other way.” The speaker of the Commons, Lindsay Hoyle, said last week that threats and intimidation against British politicians were at a level that he had “never seen anything as bad”. The Labour MP Jess Phillips said she had to make regular calls to the police during the election campaign as her supporters had tyres slashed and were filmed in the street. Her victory speech was subjected to boos and heckles. The justice secretary, Shabana Mahmood, said masked men had disrupted a community meeting, “terrifying” people in attendance. In her acceptance speech she said it had been “a campaign that was sullied by harassment and intimidation” and called the behaviour an “assault on democracy itself”. Rushanara Ali, the Labour MP for Bethnal Green and Stepney, said she needed police protection after being subjected to death threats and voter intimidation and Stella Creasy, the MP for Walthamstow, had a window and door at her office smashed days before the general election. Reform UK accused the police of failing to protect its candidates on the campaign trail. Its leader, Nigel Farage, had a milkshake and other objects thrown at him by critics. It claimed one candidate was “robbed, punched and kicked”, in what it said was a “hate crime” and that another was told to “go home” by police while leafleting. The Home Office said: “Political intimidation and abuse must have no place in our society. We take reports of intimidation, harassment and abuse extremely seriously and are following up with individual MPs and candidates.”