And No10 did not deny reports last night that the PM is looking again at charging £10 for a GP appointments to stop cancellations.
Mr Sunak suggested the idea during last year's Tory leadership campaign and sources say he still believes it would be the right thing to do - but very hard to implement.
The tough new anti-smoking measures would see the smoking age increased by a year every year to eventually make it illegal for anyone to buy cigarettes.
The plan was rejected by ministers when suggested previously, but is now understood to be on the table.
But last night it was slammed by campaigners, who said it would fuel black market.
Simon Clark, director of the smokers' group Forest, said: "Prohibiting the sale of cigarettes to future generations of adults won't stop people smoking. It will simply drive the sale of cigarettes underground and into the hands of criminal gangs.