Taxpayers are on the hook for another five-figure bill to cover Boris Johnson’s legal fees during the inquiry into his Partygate denials, as Rishi Sunak’s government prepares to extend support for the former prime minister for a second time. Labour said the move would spark outrage given the hardship being experienced by many during cost of living crisis, and pointed to the millions Johnson has earned since he left No 10 in September. The inquiry into claims Johnson misled parliament by denying any Covid rules were broken is progressing more slowly than hoped, having been beset by a series of delays. In a controversial move, senior civil servants signed off a contract initially worth £129,000 to provide taxpayer-funded legal support to Johnson during the investigation by the privileges committee. An extension to the contract was ordered in December 2022, at an extra cost of £90,000. The Guardian has been told that the contract will be renewed again, as it is due to expire on 28 February, potentially at a further five-figure cost. No official date has yet been set for public hearings, at which Boris Johnson will be called to give evidence. Officials are also preparing for the cabinet secretary, Simon Case, to be summoned as part of the inquiry. Sources have said the committee hopes to begin its televised sessions in March. Government insiders argue that the contract for Johnson’s legal advice is being extended because of the slow pace of the privileges committee’s inquiry. But that defence has been criticised because the Cabinet Office itself was accused of holding up progress by taking four months to hand over a major cache of evidence. Angela Rayner, Labour’s deputy leader, criticised the decision to fork out £220,000 on Johnson’s legal fees with the potential for another sum to cover the next expected extension. She told the Guardian: “Ministers must come clean on the nature of this contract, explain who it was agreed by and why it has been allowed to continue unchecked on Rishi Sunak’s watch. “As families up and down the country are anxious about paying their bills, they will be justly outraged at the prospect of having to foot the bill yet again for Boris Johnson’s Partygate defence fund. Rishi Sunak is showing once again that he’s too weak to put a stop to it.” The Cabinet Office declined to comment or speculate on the contract, as it is a commercial matter. The government has repeatedly said that there is an “established precedent” that former ministers can be supported with legal representation after they have left office, when matters relate to their work in government. Johnson has wasted no time since leaving Downing Street to rake in payments for speeches and a book deal on his memoirs. He has declared extra earnings of £4,785,292 in the months after he stepped down. A source close to Johnson said he was continuing to cooperate with the committee, but claimed it was yet to particularise any evidence it is proposing to rely on. The former prime minister said earlier this month that anyone who thought he had been “knowingly going to parties that were breaking lockdown rules in No 10” or covering up the gatherings was “out of their mind”. An attempt to launch a judicial review of Scotland Yard’s investigation into Partygate failed on Wednesday, after a judge dismissed the application brought by the Good Law Project that claimed there were some key flaws made by the Operation Hillman team. Danny Friedman KC argued it was “illogical” that the police had not issued Johnson with a questionnaire for three events he was later discovered to have attended, or fined him for attending them despite other Downing Street staff who were there being given fixed-penalty notices. He said the Met had not disclosed its reasoning behind either decision. But the judge refused the application, saying the police had been clear there was no “one-size-fits-all” approach to dealing with those alleged to have broken Covid rules, and said there was no arguable case of any legal flaws. Johnson received one fine, for a birthday gathering held for him in the cabinet room on 19 June 2020.