No teenagers will be sent to prison for avoiding the Conservatives’ proposed “mandatory” national service, James Cleverly has insisted. The UK home secretary said young people would face no criminal sanctions if they refused to join the military or do volunteer work under the Tories’ plan. In the first major policy announcement of his election campaign, Rishi Sunak pledged to introduce a form of mandatory national service whereby 18-year-olds would either join the military for 12 months or do volunteer work at weekends. The prime minister said the policy would help unite society in an “increasingly uncertain world” and give young people a “shared sense of purpose”. The announcement was met with ridicule and drew questions about what sanction there would be for teenagers who refused. “There’s going to be no criminal sanction. There’s no one going to jail over this,” Cleverly told Sky News’ Sunday Morning with Trevor Phillips. “This is about dealing with what we know to be the case, which is social fragmentation. Too many young people live in a bubble within their own communities. They don’t mix with people of different religions, they don’t mix with different viewpoints.” Labour dismissed the proposal as unserious and “another unfunded commitment”. The Tories said it would be paid for by cracking down on tax avoidance and evasion. “External figures assess that we will be able to capture £6bn, £1bn of which would be set aside for this,” Cleverly told the BBC’s Laura Kuenssberg on Sunday. Tory estimates said introducing the policy would cost £2.5bn a year by the end of the decade. The remaining £1.5bn would come from extending the UK Shared Prosperity Fund, which was designed to regenerate underfunded towns around the UK. Nigel Farage, the honorary president of Reform UK, said the proposal for mandatory national service was a “joke” and designed to appeal to his party’s voters. “You follow what the focus groups say – you say, by doing this I can attack the Reform vote. That’s what it’s all about. And look, it’s totally impractical. The army has shrunk from 100,000 to 75,000 in 14 years of Conservatism,” Farage told Sky. The Conservatives said that under the plans, young people who opt to do volunteer work over military service could help their local fire, NHS or police services – for example as special constables – or charities tackling loneliness and supporting elderly people. Teenagers who choose to sign up for a placement in the forces would “learn and take part in logistics, cybersecurity, procurement or civil response operations”, the party said. Two police sources said they were unaware of any consultation by the government before the plans were announced. Usually, special constables – the volunteer part-time force that supports regular policing – require training. For the Metropolitan police that involves either a part-time option of 23 days across 13 weekends, or as a full-time course lasting four-and-a-half weeks. Some are trained and allowed to carry Tasers, the electric stun gun. Sunak is trying to make global security a dividing line in the general election. On Saturday, he said voters would be left “at risk if Labour win”. Labour pointed out that David Cameron introduced a similar scheme without a military component – the National Citizen Service – when he was prime minister. “This is not a plan – it’s a review which could cost billions and is only needed because the Tories hollowed out the armed forces to their smallest size since Napoleon,” a Labour spokesperson said. “Britain has had enough of the Conservatives, who are bankrupt of ideas, and have no plans to end 14 years of chaos. It’s time to turn the page and rebuild Britain with Labour.”