The merger of Vodafone and Three has been granted conditional approval to form the UK’s biggest mobile network.

The regulator, the Competition and Markets Authority (CMA) issued the go-ahead despite having previously raised concerns that the deal could lead to increased costs for millions of customers.

However, Vodafone’s chief executive Margherita Della Valle has insisted the merger would not cost the public purse or raise consumer bills.

Speaking on the BBC’s Today programme on Radio Four, she said that the “self-funded” deal meant “no extra costs from public funding and no extra cost for our customers”.

The deal, which is reported to be worth £16.5 billion, will see the rivals come together to form the biggest mobile network in the country, with a total of 27 million customers.

The CMA has laid out several legally binding commitments that the companies must meet for the merger to proceed.

They include an obligation to invest heavily in the UK’s mobile network infrastructure. Specifically, the companies are expected to invest billions in the country’s 5G capabilities over the next eight years.

They will also be required to cap selected mobile tariffs and data plans for three years.

That is intended to protect “large numbers” of customers from price rises, although the CMA has not detailed which tariffs and plans will be protected.

The CMA watchdog said it now believed the merger would be “likely to boost competition” in the sector.