LONDON (AP) — U.K. Prime Minister Rishi Sunak on Wednesday proposed raising the legal age that people in England can buy cigarettes by one year, every year until it is eventually illegal for the whole population and smoking will hopefully be phased out among young people.

Setting out his plan at the annual Conservative Party conference, Sunak said he wanted to “stop teenagers taking up cigarettes in the first place.”

It is currently illegal for anyone to sell cigarettes or tobacco products to people under 18 years old throughout the U.K.

Sunak’s office said the incremental changes would stop children who turn 14 this year and those younger than that now from ever legally being sold cigarettes in England.

If Parliament approves the proposal, the legal change would only apply in England — not in Northern Ireland, Scotland and Wales.

“People take up cigarettes when they’re young. Four in five smokers have started by the time they’re 20,” he said. “Later, the vast majority try to quit ... if we could break that cycle, if we could stop the start, then we would be on our way to ending the biggest cause of preventable death and disease in our country.”

The government said that smoking won’t be criminalized, and the phased changes mean that anyone who can legally buy cigarettes now won’t be prevented from doing so in the future.

The number of people who smoke in the U.K. has declined by two-thirds since the 1970s, but some 6.4 million people in the country — or about 13% of the population — still smoke, according to official figures.

Britain’s government raised the legal age of sale for tobacco from 16 to 18 in 2007. That succeeded in reducing the prevalence of smoking among 16 and 17-year-olds by 30%, Sunak’s office said.

Health experts welcomed the prime minister’s plan to steadily increase the legal smoking age. A similar measure was approved in New Zealand last year.

“This government’s plan to introduce ‘smoke-free generation’ legislation could become its defining legacy, righting a century-old wrong, with tobacco products being the only legally available commodity that, if used as intended, will kill over half of its lifelong users,” said Lion Shahab, an academic who co-directs the tobacco and alcohol research group at University College London.

Sunak also said his government would introduce measures to restrict the availability of vapes, or e-cigarettes, to children. It is currently illegally to sell vapes to children under 18 in the U.K., but officials say youth vaping has tripled in the past three years and more children now vape than smoke.

Officials will look into options, including restricting flavored vapes and regulating packaging and store displays to make the products less appealing to young people.

Shares in tobacco firms fell after Wednesday’s announcement. Dunhill and Lucky Strike owner British American Tobacco saw its shares slide from roughly flat to 1% lower immediately after the announcement, while Imperial Brands saw shares fall 2.4% after Sunak’s speech.