The deal will give Imperial swift access to the US market

Commonwealth is the fourth-biggest cigarette maker in the US, owning brands such as US Gold and Sonoma.

Imperial said the deal was consistent with its strategy of entering the US market in a "low-risk" manner.

The firm said it could now avoid the estimated $20m-a-year costs of increasing sales in the US by itself.

"Commonwealth Brands is a terrific, young business which gives us immediate and significant access to the world's most profitable tobacco market," said Imperial Tobacco chief executive Gareth Davis.