Boris Johnson was accused of “stoking fear and division” ahead of a weekend of Black Lives Matter demonstrations after he unequivocally condemned the removal of historic statues and claimed the protests had been “hijacked by extremists intent on violence”. As statues – including of Winston Churchill – were boarded up to protect them ahead of planned marches, the prime minister tweeted his opposition to those calling for memorials with links to slavery and racism to be torn down. “We cannot now try to edit or censor our past. We cannot pretend to have a different history. The statues in our cities and towns were put up by previous generations,” the prime minister wrote. “They had different perspectives, different understandings of right and wrong. But those statues teach us about our past, with all its faults. To tear them down would be to lie about our history, and impoverish the education of generations to come.” Johnson said “we all understand” the “legitimate feelings of outrage” about the police killing of George Floyd in the US last month, but “the only responsible course of action” was to stay away from this weekend’s protests, which he said had been “hijacked by extremists intent on violence”. The comments, set out in eight tweets, marked a significant escalation in his criticism of the protesters, and sparked a backlash ahead of a potentially febrile weekend, amid concerns over clashes between anti-racist campaigners and “hate groups” including the far-right. The shadow home secretary, Nick Thomas-Symonds, urged Johnson not to be “found wanting” at what he called “a powerful moment in our history”. Warning that briefings with the police this week had highlighted the risk of “violence on our streets,” he said: “The prime minister should be showing national leadership, by coordinating the government’s response to the complex issues underpinning these protests. “This means recognising the deep hurt so many black people in our country have spoken so powerfully about, and setting our steps for meaningful action against racism in our country.” Christine Jardine, the Liberal Democrat MP and home affairs spokesperson, said: “The Black Lives Matter protests following the horrific killing of George Floyd by a police officer have been overwhelmingly peaceful. The prime minister is stoking division and fear in our communities by suggesting they have been hijacked by extremists.” The Green MP Caroline Lucas said: “When Boris Johnson was elected last year, he promised he wanted to unite our country. Instead he is taking yet another leaf straight out of Trump’s playbook, and deliberately whipping up his base, to divide and polarise our communities.” Johnson’s intervention came amid pressure from Tory backbenchers to take a tougher line with protesters. Ben Bradley, MP for Mansfield, tweeted: “This attack on our history [and] our culture [is] increasingly aggravating my constituents. Government need to be absolutely clear and firm on this if we are to keep a lid on increasing tensions.” Ministers have stressed repeatedly that gatherings of more than six people remain illegal under coronavirus regulations. But protesters said they would not be deterred. While a BLM protest planned for Saturday was called off after busloads of far-right activists were set to descend on London, anti-racist campaigners vowed to keep demonstrating. Tyrek, 21, an organiser with All Black Lives UK, said of Johnson’s tweets: “This isn’t going to stop us from going out on the streets. It’s within our right to protest. Women’s rights has come from protesting, LGBT rights has come from protesting, any big change has come from protest.” The protests across the country have been organised sporadically and by individuals not associated with established anti-racist groups in the past two weeks. The organisers of these protests, largely young students, have come together under the umbrella of All Black Lives UK. They are working to facilitate more localised protests. “We’ve built up momentum from the protests we’ve had and we intend on protesting as much as we can until the government responds to our concerns,” Tyrek said. “This isn’t a fad, this is a movement. It’s got steam now and it is going to continue going ahead.” On Friday, fresh graffiti appeared on road signs on Penny Lane in Liverpool over claims they are linked to slave merchant James Penny, and on a statue of Robert the Bruce at the site of his most famous battle at Bannockburn. It was painted with the slogan BLM and the words “racist king”. Robert the Bruce was king of Scotland from 1306 until his death in 1329 and led Scotland during the first war of Scottish independence against England, centuries before the transatlantic slave trade began. Some leftwing Labour MPs have been keen to see the leadership weigh in on the row more robustly. Backbencher Clive Lewis, who signed a letter to Priti Patel this week accusing her of “gaslighting” and shutting down debate after citing her own experience of racism, said he hoped his party’s leadership would continue to speak out. “Keir’s taken the knee: he’s picked a side,” he said. He called for the history curriculum to be changed, so that pupils are taught “the dark side” of Britain’s past – and questioned the use of the word “patriotism”. “The word patriotism, which Keir came out with the other day: if you take it literally, it means fatherlandism. It’s about colonialism. It’s about empire. It’s jingoistic. It’s got lots of connotations. I think we need to unpack it.” He said Labour should be trying to present “an inclusive idea of what what it means to be British”. Crowds in Bristol pulled down a statue of slave trader Edward Colston last weekend, sparking a nationwide debate about the future of scores of other monuments to controversial historical figures. All Labour councils in England and Wales announced a review of monuments’ links to slavery. The Turner-prize winning sculptor Anish Kapoor described Johnson’s opinion on statutes as “bullshit”, telling the Guardian: “Statues are not history, they are emblematic monuments to our past which can be thought to represent how we see ourselves and our history. It is long overdue that we reassess these emblems and get rid of the bigots they portray. “We must acknowledge the horror perpetrated in our names by these horrid individuals and seek to find nobler ways to make spaces of commemoration and history. This must now mean looking at the forgotten amongst us.” The perceived threat to the Churchill statue in Parliament Square, Westminster, which was daubed with graffiti at the weekend, was the focus of tweets by the prime minister. Anti-racist campaigners monitoring hate speech say far-right groups have been using the graffiti to stir anger among supporters and would-be recruits. BLM organisers said they had decided to call off a planned protest at Hyde Park at 1pm on Saturday, and in a video message to supporters, the far-right extremist Tommy Robinson said he would now not be travelling to the capital as it “would be detrimental to racial tensions”. Police are still expecting protests and laid out conditions that would keep the two sets of demonstrators apart, setting out different routes that they must follow. They ordered that both sets of marchers must disperse by 5pm. But discussions on far-right online forums and those of some football gangs have now turned to mobilising in other cities and towns including Leeds, Bristol and Sunderland against perceived threats to contested historical monuments. Far-right activists have also discussed targeting statues such as that of Nelson Mandela, perceived to be associated with their opponents, according to researchers at the campaign group Hope not Hate. “Many on the far-right who tried to pretend they didn’t care about race, only culture and identity, let the mask slip and openly started talking about whiteness and race again and threatened to pull down the statue of Nelson Mandela in Parliament Square,” said Nick Lowles, Hope not Hate’s chief executive.