The prime minister has denied that a decision has already been taken on plain packaging for tobacco products, according to the smokers’ lobby group Forest.

Earlier this week a newspaper report claimed “a senior Whitehall source” confirmed that legislation would be announced in the Queen’s speech in May.

Forest reports that speaking at a meeting in West Yorkshire David Cameron responded to a question from a tobacco packaging manufacturer by telling his audience: “We have to treat people and businesses fairly, and we should properly consider all of the statistics and all of the evidence before making that decision.” He added: "The decision has not been taken".

Welcoming the prime minister’s remarks, Simon Clark, director Forest, which runs the Hands Off Our Packs campaign, said: “There is no credible evidence that plain packaging will have any impact on youth smoking rates or encourage existing smokers to quit.

“Legislation must be evidence-based and we hope David Cameron’s comments represent a more pragmatic, less dictatorial approach to policy making.”