Powers to issue £100 on-the-spot fines are to be handed to council officers enforcing a landmark law banning future generations from smoking, which Rishi Sunak has hailed as a chance to “save thousands of lives and billions of pounds”.

The prime minister’s plan will raise the legal age of smoking every year by a year across the UK so that eventually no one will be able to buy tobacco.

Children turning 15 this year, or younger, will be banned from being sold tobacco under the tobacco and vapes bill, which is being introduced on Wednesday despite warnings of opposition from some Conservative MPs.

In a move that could prompt further anger, the bill will also strengthen the powers of council enforcement officers who monitor and investigate retailers, giving them the power to levy £100 fines for the new offence.

This is in addition to the maximum £2,500 fine which local authorities can impose on shops and other traders. It will also be illegal to give out free samples of vapes to under-18s.

“If we want to build a better future for our children we need to tackle the single biggest entirely preventable cause of ill health, disability and death: smoking,” Sunak said.

“That is why, alongside new measures to curb the alarming rise in youth vaping, we are delivering on our commitment to create a smoke-free generation and stop our kids from getting hooked on harmful cigarettes and other nicotine products.

“This important change will save thousands of lives and billions of pounds for our NHS, freeing up new resources than can be spent to improve outcomes for patients right across the UK.”

Greg Smith, a Tory backbencher, said the extra powers for councils to issue fines risked irking core Conservative voters such as small businesses.

“We are a libertarian party, or many of us are and this is not a very liberal measure,” he said. “I would anticipate there will be a significant bite-back. There could be upwards of 80 MPs on the Conservative benches opposing this.

“I’m not a smoker, nor have I ever been, but I do recognise that this is about telling adults what they can and can’t do. It’s also going to place extra pressures on small businesses at a time when they are facing significant additional overheads.”

The former prime minister Liz Truss is among those who have already signalled they will oppose the plans. If a Tory rebellion grows, the bill may rely on support from Labour to pass.

Downing Street heralded the introduction of the bill with the release of statements from charities and the chief medical officer for England, Chris Whitty.

“Smoking causes harm across the life course. This includes stillbirth, asthma, heart disease, chronic obstructive pulmonary disease, 15 different types of cancer, stroke and dementia.

“If passed this will be a major public health measure which reduces illness, disability, and premature deaths for children today and future generations.”

Deborah Arnott, chief executive of Action on Smoking and Health (Ash), described the legislation as “groundbreaking”.

“Smoking is the silent killer that hides in plain sight, killing more people than Covid at the height of the pandemic. Ending this scourge on society cannot come soon enough,” she said.

The number of people who smoke has dropped dramatically over the last 50 years as a result of concerted government action, rising awareness of the risks involved and the cost of tobacco.

In 1974 across the UK, 46% of all adults smoked. But by last year that proportion had fallen to just 12.9%. Similarly, the proportion of 11 to 15-year-olds who smoke has fallen from 19% in 2000 to 3% in 2021.

However, about 350 young adults aged 18-25 across the UK still start smoking regularly every day, according to an analysis for Ash by researchers at University College London published earlier this month.

The government has also committed to ban the sale and supply of disposable vapes from April 2025 under separate environmental legislation.

• The headline of this article was amended on 20 March 2024. It is retailers who face on-the-spot fines, not “youngsters” as an earlier version said.