Tim Yeo, the chair of parliament’s energy watchdog has written to the head of the competition body which is running a probe into the UK’s electricity market, Lord Currie, to ask why it isn’t examining the wholesale gas markets.

In his letter, the influential Tory backbencher says “no stone should be left unturned” in the inquiry.

The Competition and Markets Authority is investigating whether the way energy is bought and sold could affect energy prices for consumers. Analysts describe it as “painful but necessary” for the industry.

In the letter dated 30 July, Yeo writes: “I am surprised that the CMA has suggested that it is ‘not minded to investigate’ the wholesale gas market and I am writing to urge it to reconsider.”

He suggests the CMA competition inquiry would be “compromised from the outset” if it does not address how the wholesale market affects energy prices in the UK.

Without “as wide a ranging review as possible”, he warns “we will never restore the consumer trust that has been so badly eroded in the last five years of above-inflation price rises”.

The CMA said it will be responding to Mr Yeo’s letter soon.