Labour deputy leader seeks assurance from watchdog that it will include admission in its findings on proposed takeover.

Tom Watson, the Labour deputy leader, has written to the Competition and Markets Authority calling for its report on 21st Century Fox’s proposed takeover of Sky to include an acknowledgement from Rupert Murdoch’s newspaper business last week that it benefited from computer hacking.

Watson said the admission on Friday from Murdoch’s News Group Newspapers, the publisher of the Sun and the now-closed News of the World, was “highly significant and relevant” and he wants a written assurance that the CMS will include it in the findings of its investigation.

In a letter to Andrea Coscelli, the chief executive of the CMA, Watson said: “With this admission of guilt we can now add computer hacking to the ever growing list of criminal activity engaged in by the Murdoch media empire. These crimes may be historic, but as the Murdochs attempt to expand their reach and power through Fox’s bid for the remaining stake in Sky that they do not already own, they are highly significant and relevant.

“They are not only examples of criminal behaviour, but of corporate governance failure, and demonstrate the lengths members of the Murdoch family, who occupied senior executive positions at the company, were prepared to go to in order to avoid the truth coming to light.”

In a hearing at the high court on Friday, News Group admitted that a private investigations firm had hacked the computer of a former army intelligence officer, Ian Hurst, in 2006 and that its boss, Jonathan Rees, had then sent intercepted information to the newspaper publisher.

Lawyers for News Group said the company offered its “sincerest and unreserved apologies” to Hurst and his family and accepted “vicarious liability” for the hacking. News Group will pay “substantial” damages to Hurst and cover his legal costs.

Watson said: “They chose to fight Mr Hurst’s claim in court rather than taking responsibility for the crimes that took place on their watch.

“As the phone-hacking scandal demonstrated, this is not an isolated incident but a pattern of behaviour. It is important that there is public and political faith in the CMA investigation and that you take all relevant evidence, including Friday’s settlement, into account.”

The CMA is considering Fox’s proposed purchase of the 61% of Sky it does not already own after Karen Bradley, the culture secretary, referred the deal to the competition watchdog.

The CMA will consider the deal on the grounds of media plurality and broadcasting standards. The Murdochs have already been cleared as fit and proper owns of Sky by Ofcom, the media regulator, although the campaign group Avaaz is seeking a judicial review of this decision.

The investigation will last up to six months. One of the CMA’s first steps, which will occur in the next few weeks, will be to publish an issues statement that clarifies the depth and breadth of the investigation.