New research from The Information Centre reveals that 65% of under-16s who smoke cited shops as their main source of supply.
The study found that 55% of 11- to 15-year-old smokers bought cigarettes from a news-agent, tobacconist or sweet shop, while 24% purchased them from a forecourt store, and 21% from a supermarket.
However, while the purchase figures remain high, the proportion of youngsters overall who have tried to buy cigarettes from a shop in the past year has steadily declined from 32% in 1990 to 17% in 2006, showing that retailers' efforts to crack down on underage sales are proving effective.
The report comes only a month before the minimum legal age for buying tobacco increases from 16 to 18 on October 1.
Association of Convenience Stores (ACS) chief executive James Lowman has renewed his call for retailers to stamp out underage sales of tobacco through a strict No ID No Sale policy.
"Stopping children from buying age-restricted products is a core part of being a responsible retailer," said Lowman. "However, there is still much more that needs to be done."
He also advised retailers to immediately start adopting a Challenge 21 stance for tobacco, in line with alcohol.
"Only by enforcing a strong No ID No Sale policy on all age-restricted products can we stop those who are underage getting hold of these products," he added.
l For more on how retailers are preparing for the increase in the legal purchasing age for tobacco, turn to p37.