A six-month test purchasing operation by trading standards officers across England found one in five retailers guilty of selling cigarettes to children.
In total, 457 sales to underage children were made during test purchases this year, compared with 241 the previous year.
All types of retailers were targeted during the operation, with vending machine operators faring the worst, failing 41% of all test purchasing visits. The next worst culprits were independent newsagents, with almost a quarter (23%) found selling tobacco products to children.
Convenience store owners can take some comfort from the fact that they performed better than the supermarkets. Illegal sales were made in 15% of convenience stores tested, compared with 19% in supermarkets.
New tobacco banning orders to be introduced next year will see retailers face bans of up to a year if caught breaking the law.