British Gas will take on 90,000 customers left without an energy supplier after Rebel Energy went bust earlier this month.

The industry regulator for Great Britain, Ofgem, on Sunday appointed British Gas to begin supplying gas and electricity to 84,000 household customers and 6,000 businesses.

British Gas saw off competition from other energy companies to inherit the customer base less than a week after Rebel Energy blamed a “perfect storm” of soaring wholesale prices and squeezed customers for going under.

Dan Bates, the founder of Rebel, said in a social media post that the company was “regrettably” not able to raise the required capital to secure the future of the business, which “ultimately means that Rebel Energy will be going out of business”.

The small boost to the number of British Gas customers has come weeks after the company was toppled from its position as the UK’s largest household energy supplier for the first time in almost 40 years by the rival Octopus Energy.

An industry report by Cornwall Insight found that Octopus grew its share of the market to 23.7% of households in Great Britain by the end of last year, while British Gas held a 23.1% share of the market, or 320,000 fewer accounts than Octopus.

Weeks later Chris O’Shea, the chief executive of the British Gas parent company, Centrica, said that its fall in the market league table “should galvanise my wonderful colleagues at British Gas”.

O’Shea said on Monday: “We’re looking forward to welcoming thousands of customers of Rebel Energy to British Gas, and we’ll ensure the switchover is as smooth as possible. We’re a brand trusted by millions, and our new customers will benefit from the range of advantages that come with being a British Gas customer, including access to exclusive offers on services like boiler cover, Hive products and PeakSave.”

Tim Jarvis, a director at Ofgem, said: “While I know customers may be concerned, they do not need to worry. All credit balances remain protected, and there will be no interruption to their energy supply while the switch is taking place.

“Rebel Energy customers will be placed on to a competitive tariff, though should consider what’s right for them once the transfer is complete. They will also face no exit fees if they choose to switch to another supplier.”