The age at which people can buy cigarettes and tobacco in England should rise by one year every year so that eventually no-one can buy them, the prime minister says.
Rishi Sunak said MPs were to be given a free vote in parliament on the issue.
Under the plan, the age of sale would rise from 18 every year so a child aged 14 today would never be allowed to buy tobacco.
The idea was put forward by a government-commissioned review in 2022.
Speaking at the Conservative party conference, Mr Sunak said he believed it was the right step to tackle the leading cause of preventable ill-health.