The Competition Commission’s final ruling on Thomas Cook’s merger with the Co-operatives may be delayed until October despite the provisional go-ahead last week.

The Commission announced an eight-week extension of the timetable for its investigation yesterday, moving the deadline from August 16 to October 11.

Thomas Cook had hoped to complete its retail merger with The Co-operative Travel and Midlands Co-operative by October, a process likely to take about six weeks from the final ruling. The deal would create a chain of more than 1,200 high-street agents.

The Competition Commission gave provisional clearance on July 21. It is not expected to change that, and the deadline for final submissions on the merger remains August 11.

A Competition Commission spokesman said the extension was solely to give time to consider any detailed submission. The spokesman said: “We have to give this proper consideration. Five days wasn’t very long to do anything but publish the final report. We have to run a fair process.”

He added: “The provisional findings were published quite late compared with the normal schedule. Taking the appropriate time to consider responses is going to take us past the original deadline.”

An eight-week extension was the only option, he said. However, the Commission could issue its final ruling ahead of the new deadline. The spokesman said: “We would aim to complete things sooner than that.”

Thomas Cook appeared unfazed by the announcement. A spokeswoman said: “It is not unexpected. All being well it should not delay the completion date.”

The company originally announced the deal last October and hoped to complete it in time for savings to be included in accounts for the current financial year which ends in September.