Canadian Prime Minister Justin Trudeau was hit by a handful of gravel on Monday, television images show, as he made his way to his campaign bus past a crowd shouting their opposition to Covid-19 vaccines. A camera captured what looks to be white gravel hitting Mr Trudeau and one of his bodyguards as he walked towards his campaign bus in London, Ontario. The Liberals cancelled an event last month because of safety concerns linked to anti-vaccination protesters. Mr Trudeau played down the incident on his plane later, saying he may have been hit on the shoulder. On Monday, Mr Trudeau assailed Conservative leader Erin O'Toole's opposition to vaccine mandates, including for his own candidates, and called the hecklers “angry mobs". “Erin O'Toole is at least taking some of his cues from [the anti-vaccination crowd]," Mr Trudeau said. About 74 per cent of eligible Canadians have been fully vaccinated, but a fourth wave of the coronavirus pandemic is currently building, mostly among the unvaccinated. The prime minister also criticised Mr O'Toole on Monday for waffling on gun control as <a href="https://www.thenationalnews.com/world/us-news/2021/08/15/trudeau-calls-canadian-election-for-september-20/" target="_blank">the campaign enters its final stretch before the September 20 election</a>, with the Liberals and Conservatives running virtually neck and neck in the polls. Mr O'Toole on Sunday scrapped a campaign promise to eliminate a ban on some assault weapons, a sensitive issue in Canada after several mass shootings in recent years. Mr Trudeau sought to capitalise on his opponent's shift with only two weeks left to reverse his fortunes. The conservative Mr O'Toole “will say anything to try to get elected,” Mr Trudeau told supporters at a campaign event in southern Ontario, Canada's most populous province. “That's not leadership. That's not integrity.” Speaking in Ottawa, Mr O'Toole refused to say how many of his candidates had not been inoculated. He has said those who are not vaccinated must be tested daily. “Our approach, with respect to vaccinations, is we try to encourage and inform and work with people, but we will respect their personal health decisions,” Mr O'Toole said. Liberal strategists have said the crucial period of the campaign starts after Labour Day, because Canadians have been more focused until now on their summer holidays than the election. There are two debates this week, one in French and one in English, the only occasions left in which all the candidates will face one another on national television before the vote. A rolling Nanos Research survey of 1,200 people for CTV on Monday put the Liberals at 34.1 per cent and the Conservatives at 32 per cent, a reversal from a day earlier, when Liberals were at 33.4 per cent compared with 34.9 per cent for Conservatives.