Telecoms business Cellnex will have to sell around 1,000 mobile towers in order to buy the company behind Three’s mobile network in the UK, after the competition watchdog warned it could push up prices for mobile users.

The Competition and Markets Authority said that the £8.6 billion European deal for CK Hutchison will only be allowed if it sells off parts of the network in the UK.

The sale would have prevented the emergence of an important competitor for supplying this infrastructure, and could push up prices for mobile networks.

In turn this could lead to higher prices or lower quality services for mobile phone users, the CMA found.

Richard Feasey, chair of the CMA’s independent inquiry group, said: “Our decision today helps protect competition in infrastructure that mobile phone operators rely on.

“The sale of this significant package of assets will allow a major supplier to compete against Cellnex when mobile networks look to negotiate new contracts in future.

“This, in turn, stops the threat of higher prices or worse terms for the operators and their customers as a result of this deal.”

It was Cellnex itself which proposed the sale of the sites, which overlap with those it has agreed to buy from CK Hutchison, the CMA said.

This would be enough to “effectively address the competition concerns identified by the investigation”, the CMA said.

The inquiry was launched in May 2021.