The report was first expected to be published last autumn and has since been postponed several times. The CC is under a statutory obligation to publish its findings by 8 May 2008.
Association of Convenience Stores (ACS) chief executive James Lowman said: "We welcome this latest delay, because there remain a number of issues that the Commission has to work through, especially its provisional finding that the trend in store numbers in the convenience market may be on the increase.
"We have submitted a strong rebuttal and significant new evidence on this and other issues. We are glad that the Commission will have more time to consider them."