Dominic Cummings has been accused of wrongly carrying out work for the Conservative Party when he is paid by the taxpayer, in a new controversy to hit Boris Johnson’s chief aide.

Chuka Umunna protested that reports that Mr Cummings was conducting focus groups – to road-test slogans for an autumn general election – suggested he had broken the rules.

Meanwhile, the Cabinet Office has rebuffed a freedom of information request which would confirm that Mr Cummings is paid from taxpayer funds, the Liberal Democrat MP said.

If he is paid by the Conservative Party, it would raise different questions about the security access the former Vote Leave chief enjoys in Downing Street, Mr Umunna claimed.

Raising a point of order in the Commons before it shut down, he said: “Under the civil service code of conduct, government special advisers who are government employees paid may not undertake work for a political party during office hours.

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“They should also not use official resources for party political activity.

“Based on widespread reports, it appears that the prime minister’s chief special adviser, Mr Dominic Cummings, almost certainly has undertaken work for the Conservative Party while carrying out his duties.”

The allegation follows the reports that Mr Cummings has held a series of focus groups in the past two weeks to assess voter reactions to the slogan ‘Trust the People’.

Although the prime minister was thwarted in his bid for a mid-October election, a poll before Christmas remains highly likely – after, rebel MPs hope, Brexit has been delayed beyond the current 31 October deadline.

Furthermore, Mr Johnson remains in electioneering mode, launching a new wave of ‘free schools’ on the back of a spending round that drew a line under the austerity programme.

Mr Umunna protested that the Cabinet Office had replied to his freedom of information request by saying he must wait until December for the information, saying: “That is clearly unsatisfactory.”

The former Labour MP had also tried to find out, if Mr Cummings is not paid from public funds, “does he have the same access to Downing Street and the civil service”.

However, the Cabinet Office decided there was “no overriding public interest” in pre-empting the standard publication date for full details of special advisers’ pay, which is in December.

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The Independent understands that Mr Cummings is, like almost all special advisers, paid exclusively from taxpayer funds.

Downing Street has been asked to respond to the allegation.

The row comes amid anger that Mr Cummings has been granted a security pass for the Palace of Westminster despite having been found in contempt of parliament.