Small shop leaders have rounded on the Competition Commission for concluding the number of convenience stores is on the up in the week that a new report showed a further decline in the market.

In the final report of its two-year investigation into the groceries market, the commission concluded "the number of convenience stores had not declined in recent years". It used Office for National Statistics data, which found the number of c-stores operated by small businesses had increased by 3% between 2003 and 2007 - from 33,394 to 34,505.

But it rejected figures compiled by IGD, produced by The Grocer's owner William Reed Business Media (owner of The Grocer), which the industry considers the most comprehensive database available.

These figures showed the total number of c-stores had fallen from 55,798 in 2000 to 50,734 in 2007.

And the latest report, published today by IGD/William Reed Business Media, found in the year to April 2008 the total number of c-stores fell 2.4% to 49,530. The number of non-affiliated independent stores dropped 5.8% to 23,108 but the number of symbol group stores rose 4.2% to 14,340. In contrast, the number of c-stores owned by the multiples rose 3.7% to 2,604.

The commission's conclusion was "astonishing" said James Lowman, CEO of the Association of Convenience Stores. "The commission was presented with ample evidence from suppliers and wholesalers showing independent c-store numbers are in decline," he said.

"It is astonishing that after such a long investigation its understanding remains so limited. This failure has undermined the credibility of its recommendations in a number of areas."

The Commission acknowledged its findings went against popular consensus. "The ACS, and most of the other submissions that we have received on the issue of small store numbers, have suggested that we should rely on IGD/William Reed Business Media data and other industry sources," it said. "However, we have some concerns that this data may not be appropriate to identify trends in the number of c- stores.

"IGD/William Reed Business Media has improved its database in recent years, which is likely to show as a decreasing number of stores when compared year-on-year," it added.