The proportion of convenience stores passing underage alcohol compliance tests has increased by more than 20% in the past three years.

Latest results from Serve Legal, an independent test purchase service, show the pass rate for alcohol test purchases in 2010 stands at 76%, up from 55% in 2007. For tobacco products the pass rate has risen from 66% in 2009 to 70% in 2010.

Matt Eastwood of Serve Legal said the latest results were regionally consistent. Scotland topped the table with an 82% pass rate, while the worst performing region was the Midlands with a 72% pass rate.

Failure rates are more likely to be higher on busier days. The average pass rate on Saturday and Sunday is 74% and 71% respectively.

Eastwood added that the results represented "a good news story for retailers".

Significantly, the importance of the support from other staff is evident, with just 68% of shopworkers passing when working alone and 63% when without a supervisor in 2009.

The alcohol pass rate for supermarkets is 79%.