CHC Group has been ordered to unwind its completed acquisition of Babcock International’s North Sea helicopter business.

The Competition & Markets Authority said the £10 million deal, which completed in September, significantly reduced rivalry among firms serving the offshore oil rigs.

Vancouver-based CHC and Babcock Offshore were two of only four suppliers operating in Britain, said the CMA, which demanded that four players remain in the market.

Kip Meek, chairman of the watchdog’s inquiry group, said: “Offshore oil and gas are important industries for the UK, and helicopter companies play a vital role in transporting workers safely to and from oil rigs.”

Before the merger, Babcock employed about 500 people in its helicopter business based in Aberdeen, while CHC, which generated just over a fifth of its £608 million global revenues in Britain, had about 300 staff in the region.

A spokeswoman for CHC said the firm was disappointed by the CMA’s decision and said it had failed to understand the need for consolidation in a highly challenging market environment.