The acquisition of Worldpay in a deal that values it at £7bn more than the price fetched by Royal Bank of Scotland for the business seven years ago has raised concerns the taxpayer has lost out from EU state aid rules.

American payments processor Vantis on Wednesday agreed to buy its FTSE 100 rival for £9.1bn, including debt, in a deal that creates an transatlantic industry giant.

It comes after RBS sold an 80pc stake in Worldpay to private equity houses Advent and Bain in 2010 in a buyout that valued the payments business at as much as £2bn, including debt.

RBS, which remains 71pc taxpayer-owned following its bailout during the crisis, was forced to dispose of Worldpay and other businesses to meet EU rules that demanded the divestment of non-core assets.

Disposals were sought by Brussels to quell competition concerns following RBS’ £45.5bn government rescue.

In the five years before Advent and Bain listed Worldpay on the stock exchange in 2015 with a market capitalisation of £4.8bn, the pair invested more than £1bn in the payments business.

Despite that investment, MPs said that the big difference in valuations between the RBS sale and Vantiv deal sparked worries over whether the taxpayer got a good deal when RBS originally offloaded the business.