In an effort to gradually phase out tobacco use, ministers are thinking about enacting stricter laws prohibiting smoking outside.
The Sun was the first to announce that smoking might be prohibited in outdoor dining areas, sports fields, hospitals, and bar gardens.
The proposed regulations are part of a more stringent version of the Tobacco and Vapes Bill from the previous government, which would make it illegal to sell tobacco to anybody born on or after January 1, 2009.
After the general election was announced, the bill that had been introduced in Parliament was abandoned.
The measure to gradually raise the legal age of tobacco purchase was promised to be reintroduced in the King's Speech during the official opening of Parliament last month.
Secret Whitehall papers confirmed the plan to extend the indoor smoking ban despite some opposition within government.
The Department of Health and Social Care said it did not comment on leaks but was considering a range of measures to "finally make Britain smoke-free".
A spokesperson said: "We do not comment on leaks. Smoking claims 80,000 lives a year, puts huge pressure on our NHS, and costs taxpayers billions.
“We are determined to protect children and non-smokers from the harms of second-hand smoking.
"We’re considering a range of measures to finally make Britain smoke-free.”
Discussing the Sun's front page story on BBC Newsnight, Lord Stewart Wood, a former adviser to Labour's Gordon Brown, told the programme: "Lots of people don't like smoking. They are quite tough on public health."
But former Conservative special adviser Anita Boateng told the BBC: "It feels a very draconian step for people who are adults who can make decisions and who can legally smoke.
"The point is you are in an outside area of a pub garden in a walled off area. You don't have to stand there if you don't want to experience second-hand smoking."
When he was prime minister earlier this year, Rishi Sunak outlined goals to lower the number of smoking-related deaths and create a "smoke-free generation".
However, after he called the May general election, his Tobacco and Vapes Bill was shelved.
If it had been passed into law, it would not have been permitted to sell tobacco to anyone born after January 1, 2009.