Sir Keir Starmer still hasn't seen legal advice which his deputy Angela Rayner claims exonerates her over her 'two homes' row.
Ms Rayner is under mounting pressure as both police and council investigations have been launched into the saga.
It is now threatening to overshadow Labour's campaigning ahead of next month's local elections.
At Prime Minister's Questions yesterday, Sir Keir was mocked by Rishi Sunak over his claim that he does not need to see the legal and tax advice which Ms Rayner says clears her of any wrongdoing.
The Labour leader attacked Mr Sunak over predecessor Liz Truss's book, Ten Years To Save The West, calling it 'quite the read'.
At Prime Minister's Questions yesterday, Sir Keir was mocked by Rishi Sunak over his claim that he does not need to see the legal advice which Ms Rayner says clears her of any wrongdoing
Ms Rayner, 44, faces questions over whether she should have paid capital gains tax on the ex-council house when it was sold in 2015, for a £48,500 profit, if it was not her principal residence
But the PM hit back, telling MPs: 'He ought to spend a bit less time reading that book and a bit more time reading the deputy leader's tax advice.'
Mr Sunak told his opposite number to 'show some leadership' and 'simply publish' the legal advice Ms Rayner has received over the sale of her former council house in Stockport, Greater Manchester.
Ms Rayner, 44, has faced questions over whether she should have paid capital gains tax on the ex-council house when it was sold in 2015, for a £48,500 profit, if it was not her principal residence.
The allegations first emerged in Red Queen? The Unauthorised Biography Of Angela Rayner by Lord Ashcroft, serialised in the Mail and Mail on Sunday.
A Labour spokesman confirmed Ms Rayner had received separate advice on the legal and tax implications of her property dealings.
The advice has been seen by members of Sir Keir's team, but the Labour leader has not asked to look at it himself.
A spokesman for Sir Keir said he was confident Ms Rayner had 'acted within the rules' but said it was 'not for him to rule on the advice'.
Police last week launched an investigation into claims that before becoming an MP in 2015, Ms Rayner may have wrongly declared on the electoral roll she was living in a property on Vicarage Road.
Neighbours allege that she was living primarily at her then-husband Mark's home in Lowndes Lane, a mile away.
Police last week launched an investigation into claims that before becoming an MP in 2015, Ms Rayner may have wrongly declared on the electoral roll she was living in a property on Vicarage Road - but neighbours allege she was living primarily at her then-husband Mark's home in Lowndes Lane (pictured), a mile away
The police are also understood to be looking at her tax affairs, including whether she wrongly claimed a single person's council tax discount on her property while allowing her brother to live there.
However it was revealed yesterday that documentation confirming the address Ms Rayner gave while bidding to enter politics – thought to be crucial to the investigation – has been destroyed.
The mother-of-three would have had to provide an address when she applied to become the Labour candidate for Ashton-under-Lyne the year prior to the election.
A Labour spokesman told the Mail the paperwork had been 'disposed of' in line with data protection rules.
Giving false information is an offence under the Representation of the People Act 1983 but there is a time limit of a year for bringing any charge.
Magistrates can extend this in rare situations.
Ms Rayner says she and her ex-husband both 'maintained' their own properties at the time. Sources say she has 'never denied' she 'spent time' at his home.
Last week Ms Rayner said she would resign if 'found to have committed a criminal offence'.