Boris Johnson has been cleared of breaking parliamentary rules over a holiday to Mustique but was criticised for failing to offer an earlier explanation of who paid for the trip.

The UK prime minister was investigated by the House of Commons’ Committee on Standards after he said the £15,000 holiday to the Caribbean island was paid for by David Ross, the founder of Carphone Warehouse.

Johnson made the trip with his now wife Carrie in December 2019 following the last general election. Ross initially disputed that he had directly paid for the trip, but later clarified he had “facilitated” the holiday.

In a report published on Thursday, the MPs’ watchdog criticised Johnson for the “ad hoc and informal” arrangements and the “regrettable” lack of full clarity on the holiday. “This matter could have been concluded many months ago if more strenuous efforts had been made to dispel the uncertainty,” it stated.

The investigation concluded that Ross arranged for the use of Indigo, another villa on the island by Johnson via the Mustique Company. “The ad hoc agreement at the time that the benefit was conferred on Mr Johnson was that the Mustique Company would pay the owners of the villa and that Mr Ross would, in recompense, allow the Mustique Company the use of his own villa to cover the value of the accommodation.”

The inquiry concluded that Johnson had not breached parliamentary standards over the trip. It also said that the £15,000 declaration was a suitable amount for the value of the trip.

“Taking the additional new evidence into consideration, the committee concluded that Mr Ross was the donor of Mr Johnson’s holiday accommodation, the committee therefore found that Mr Johnson’s register entry was accurate and complete.” the report stated.

The report urged Johnson to be clearer in his declarations in the future. “The Committee stated that it was unsatisfactory that neither Mr Ross nor Mr Johnson explained the arrangements to the commissioner until last autumn and that Mr Ross only provided minimal information on the arrangement this spring and in response to the committee’s further enquiries.”

Speaking to reporters, Johnson declined to comment on the investigation or its findings. “As I understand it, the committee has found there was no case to answer,” he said.

Angela Rayner, the Labour deputy leader, criticised the prime minister for the “chaos and confusion” in the handling of his personal affairs.

“This whole murky affair shows Boris Johnson has a casual relationship with the truth and a flagrant disregard for the most basic standards of integrity and trustworthiness that we would expect from a prime minister,” she said.

Johnson has been censured multiple times by parliamentary authorities for late declarations of his financial interests.