Any donations Boris Johnson received over the controversial refurbishment of his Downing Street flat are expected to be published by the end of the month.

His new ministerial standards adviser, Lord Geidt said on Thursday that he is “determined” to publish the long-overdue list of ministers’ interests before May is up.

The crossbench peer told MPs that “alongside” the list he will publish his report into the declaration of any donations the Prime Minister received to help cover the costs of the lavish renovations in No 11.

The list of ministers’ interests has not been published since July last year but Lord Geidt said he is “in the process of receiving” the relevant papers.

Lord Geidt told the Commons Public Administration and Constitutional Affairs Committee: “I’m determined that it should be published by the end of this month.

“Public confidence, I think in my judgment, demands that this list be published without further delay.

“The publication of the list of interests will include the Prime Minister.”

He noted that he has also been tasked to “consider all the facts relating to the refurbishment of the Prime Minister’s flat and to advise him on his own declaration of interests”.

“I would plan to publish that advice alongside the declaration of interests,” Lord Geidt added.

He was appointed to the role last month as the Electoral Commission launched a formal investigation into the renovations, saying there are “reasonable grounds” to suspect an offence.

The post had been vacant since Sir Alex Allan resigned in November in response to Mr Johnson standing by Home Secretary Priti Patel despite an investigation finding her conduct “amounted to behaviour that can be described as bullying”.

The delay in publishing the list of interests was blamed on the post being empty, but Lord Geidt told MPs it was “unfortunate” that there was no publication in the interim.

“I do think that it was unfortunate that the list that we imagine should’ve been published in December 2020 wasn’t, and that is why I’m driven to act with as much urgency as I can to get this next list published at the end of the month,” he said.

Mr Johnson has insisted that he has paid for all the works, reported to have cost up to £200,000, himself but has refused to say whether he received an initial loan to cover them.

Opposition MPs have raised concerns that the adviser’s role is not sufficiently independent because the Prime Minister remains the “ultimate arbiter” of the ministerial code.

Lord Geidt conceded that his role does not reach full transparency but argued that his powers have been expanded over the ability to publish his advice on the ministerial code compared with under his predecessor.

He said he received an assurance “with enthusiasm” from the Prime Minister that he is “able to cause that advice to be published and, critically, in a timely manner”.

“I agree that you are clearly making an observation that sunlight doesn’t appear to shine into every corner of these arrangements and I absolutely accept what you say,” he told Labour MP Lloyd Russell-Moyle.

“But I’m very glad to have, and I was keen to secure, assurances to ensure that we could very much improve the capacity of the independent adviser to publish once the investigation has been completed.”

Lord Geidt said he is confident that the new terms of reference can be made to work.

“I would like in this role to work with the new terms of reference and really test the extent to which this can help make a contribution to public confidence,” he said.

“If it becomes apparent that that doesn’t deliver for the purpose of public confidence then I do have the licence to bring forward advice to the Prime Minister to suggest a change to those terms of reference.”