Britain’s Conservative Party will introduce mandatory national service for 18-year-olds if it wins the national election on July 4, comprising military or community participation, Prime Minister Rishi Sunak said on Sunday.

Young adults will be able to choose between spending one weekend a month volunteering over the course of a year, or take up one of 30,000 spaces to spend a year in the armed forces, Sunak said.

The announcement followed Labour Party leader Keir Starmer’s comments on Saturday that he was in favour of allowing 16 and 17-year-olds to vote.

Sunak’s Conservatives lag Labour by a wide margin in opinion polls, which have shown little change in fortunes for the prime minister since his surprise election call last Wednesday.

“Britain today faces a future that is more dangerous and more divided. There’s no doubt that our democratic values are under threat. That is why we will introduce a bold new model of national service for 18-year-olds,” Sunak said in a statement.

The Conservative Party said the proposal would be funded by cracking down on tax avoidance and evasion, and by diverting money from the UK Shared Prosperity Fund, which existed to reduce regional economic inequality.

Labour politicians derided the announcement.

“The national service we need from our young people is to vote for change on 4th July,” said Andy Burnham, mayor of Greater Manchester.

Interior minister James Cleverly told broadcasters there would be no criminal sanctions for skipping mandatory service but that people will be compelled to do it, without providing further details.

Asked by the BBC if forcing adults to volunteer was at odds with the Conservative Party’s liberal tradition, Cleverly said: “We force people to do things all the time.” He cited compulsory education or training for teenagers until the age of 18 as an example.