The first ever merger between NHS providers to be reviewed by the Office of Fair Trading was today referred to the Competition Commission for an in-depth investigation.

The OFT referred the proposed merger between the Royal Bournemouth and Christchurch Hospitals Foundation Trust and Poole Hospital FT after concluding that it would leave local patients and commissioners with “few realistic alternative providers”.

It is the first such merger to have been reviewed by the OFT since the passing of the Health Act 2012, which affirmed the competition watchdog’s jurisdiction over mergers between NHS foundation trusts.

In a statement issued this afternoon, the OFT said the merger would “combine the only two NHS district general hospitals in Bournemouth and Poole, which compete across a range of clinical specialties”.

It continued: “The evidence before the OFT is that the merger would combine two trusts that compete closely for GP referrals for many specialties and it is likely that the merger would result in few realistic alternative providers for patients and NHS commissioning groups.

“As a result, the OFT could not dismiss concerns that in several medical specialties - notably rheumatology, rehabilitation, general medicine, general surgery, geriatric medicine, dermatology, clinical haematology, oral and maxillofacial surgery, cardiology and palliative medicine - the merger might reduce the hospitals’ incentives to continue to enhance the quality of those services over the minimum required standards and would result in less choice for commissioners wishing to reorganise services.”

OFT chief executive Clive Maxwell, who was the decision maker in the case, said: “Our review found that these two foundation trusts compete with each other in a number of specialties, both to attract patients and funding from commissioners.

“We decided on the basis of the evidence available, including advice from [foundation trust regulator] Monitor, that we could not rely on the potential benefits from this merger outweighing the expected impact on patients and commissioners of a loss of competition. We have therefore concluded that a reference to the Competition Commission for an in-depth review is necessary.”

The commission is expected to report by 24 June.