Dominic Cummings, the former director of the official leave campaign, has been ruled to be in contempt of parliament after failing to appear before MPs investigating fake news.

The House of Commons committee of privileges said Cummings’ refusal to give oral evidence to MPs constituted a significant interference in the work of the inquiry.

In a statement, Cummings, who was portrayed last year in a Channel 4 Brexit drama by Benedict Cumberbatch, said he had offered to give evidence but was rebuffed.

He was responding to a committee report released on Wednesday.

MPs had examined correspondence between Cummings and the digital, culture, media and sport (DCMS) committee, which was investigating the proliferation of false news stories during the EU referendum campaign.

The privileges committee acknowledged its sanctions were limited to recommending the Commons issue a formal admonishment for Cummings’ conduct, raising questions about the committee’s enforcement powers.

The admonishment would require a resolution of the house, which, if passed, “should be communicated to Mr Cummings by the clerk of the house”, the committee said in its report.

Damian Collins, the chair of the DCMS committee, said it was clear the powers of the house had been “found wanting”.

He said Cummings – the director of the campaign spearheaded by Boris Johnson – had shown a “total disregard” for the authority of parliament and called for statutory powers to “reassert the authority that is missing”.

“The Dominic Cummings case highlights the need for parliament to define in law what its powers should be to require witnesses to attend hearings, and what sanctions should apply if they do not,” Collins said.

“The current powers have been tested to their limits and found wanting.”

The committee of privileges said the case “raised further questions about the enforceability of the house’s powers and those of its committees to secure evidence”, and that it would be resuming an inquiry into the matter.

The case was referred to the committee last June after Cummings failed to respond to an order of the house requiring him to give an undertaking to appear before the inquiry by a specified date.

In launching its inquiry, the committee said the house had previously decided its penal jurisdiction should be exercised as sparingly as possible. It added that it would not recommend the use of any “power of committal to prison” in this case.

The report concluded that Cummings committed a contempt “both by his initial refusal to obey the DCMS committee’s order to attend and by his subsequent refusal to obey the house’s order of 7 June”.

It also expressed regret for the tone adopted by Cummings in his dealings with the DCMS committee and in comments posted on his blog, which included accusations of “grandstanding” and “spreading errors and lies”.

“This attitude did not serve the interests of civilised public debate,” the report said.

“We have no doubt that, had Mr Cummings attended a hearing of the DCMS committee, he would have given robust and articulate responses to the questions put to him, and would have had no difficulty in communicating his standpoint to the public and the media.

“Attending the hearing and defending his position when called upon to do so would have been the right thing to do.”

While Cummings’ reputation may be tarnished inside the Commons by Wednesday’s report, it could well be enhanced among his followers on the libertarian right who have celebrated his battles with the political establishment.

Cummings, a former special adviser to Michael Gove, was once described as a “career psychopath” by the prime minister at the time, David Cameron.

He was widely seen as the brains behind the “£350m a week for the NHS” slogan written on Vote Leave’s red bus. The campaign group has been referred to the police for overspending on the eve of the 2016 vote.

In a blog post on Wednesday, Cummings claimed he was willing to appear before the committee but had told Collins to “get lost” after receiving a summons from the MPs.

He said he was later willing to give evidence to the privileges committee but only if both he and the MPs agreed to swear an oath.

“My offer to give evidence to MPs remains open. As does my reasonable demand that ALL OF US ARE UNDER OATH TO TELL THE TRUTH. I hope they take it up but am not hopeful,” he wrote.