The number of cigarettes sold in the UK has fallen by around 20 million a month since the introduction of new rules three years ago.

New figures from the Tobacco Control Research Group said sales had been falling by close to 12 million each month before plain packaging rules and tougher taxes were introduced in May 2017.

The decline in sales does not appear to have sparked an increase in illegal tobacco sales, which had been feared with the introduction of the changes, according to HMRC figures published by the British Medical Journal publication Tobacco Control.

Tobacco Control Research Group director Professor Anna Gilmore said: "The underlying rate of decline in tobacco sales almost doubled after these policies were implemented.

"Governments around the world considering plain packaging can be reassured that this policy works and that the real reason the industry opposes this legislation so vehemently is because it threatens its profitability.

"With coronavirus already posing a threat to tobacco company sales and plain packaging of tobacco taking off in other jurisdictions, our findings are more bad news for tobacco companies."

The Cancer Research UK and British Heart Foundation funded study found net revenue for the tobacco industry fell by 13 per cent from £231million to £198million a month.