Labour are poised to report Boris Johnson to Parliament's standards watchdog amid fresh questions over 'wallpaper for access'.
The PM is accused of promising to consider a plan for a "Great Exhibition" as a favour to Lord Brownlow, who was at the time funding the refurbishment of his flat. The PM later repaid the £112k donation himself.
Labour's Steve Reed told BBC Radio 4's Today programme: "Labour has referred this on to the Parliamentary Standards Commissioner, Kathryn Stone".
The Prime Minister faces serious questions over his Downing Street flat refurbishment after a furious letter from his ethics chief, Lord Geidt.
However, the Mirror understands that despite Mr Reed's comments, the party has not yet written to Parliament's Standards Commissioner.
Discussions are still under way about whether to make a formal referral. Meanwhile deputy leader Angela Rayner wrote today to Lord Geidt asking for a string of questions to be answered.
Shadow justice minister Mr Reed added: "Lord Brownlow appears to have had access to the prime minister because he was paying for the flat renovation. If that’s the case it amounts to corruption."
Downing Street yesterday published a humiliating “lost” WhatsApp the PM sent Lord Brownlow, begging for more cash to revamp his grace-and-favour flat.

The text exchange shows the PM asked the donor for "approvals" for the £112,000-plus makeover, moaning the flat above 11 Downing Street was a "bit of a tip” - despite the fact it had a new kitchen in the last decade.
Lord Brownlow replied promising to get on with the job, adding: "It’s only me and I know where the £ will come from".
After previously saying he didn’t know the source of the funds until three months later, Boris Johnson apologised and claimed he didn’t hand over the messages because they were on his old phone.
Lord Geidt, the independent advisor on ministers’ interests, slammed multiple failures but ultimately cleared the PM of breaching the Ministerial Code.
However, a fresh row has erupted after it emerged the pair discussed a project of the Tory donor’s in the same message exchange.
Mr Johnson wrote: “Ps am on the great exhibition plan Will revert.”


This relates to a ‘Great Exhibition’ like that held by the Victorians, which established the Crystal Palace.
Downing Street said the plan for a "Great Exhibition 2.0" was not taken forward.
Yet just two months after the PM’s text, Lord Brownlow attended a meeting with then-culture secretary Oliver Dowden to discuss his Great Exhibition 2.0 proposal.
Mr Dowden's official diary includes a meeting "with Royal Albert Hall and Lord Brownlow To discuss plans for Great Exhibition 2.0'
Labour deputy leader Angela Rayner said: “It is simply impossible to read these exchanges and conclude that the Prime Minister has not breached these aspects of the Code.
"Once again, by attempting to hide the truth, Boris Johnson undermines his own office.

“This matters because it matters who has influence on our government in a democracy. The British public can't WhatsApp a wealthy donor to open their wallets on request, and the least they deserve is transparency about who’s bankrolling their Prime Minister.”
The 'missing' messages reveal Mr Johnson had declared the luxury flat above Number 11 "a bit of a tip" - and asked Lord Brownlow to release more donor cash for a lavish, £112,000 designer refurbishment.
In a scorching letter, Lord Geidt said the failure to provide him with the texts was “plainly unsatisfactory", demonstrated "insufficient respect" and presented a "threat to public confidence" in his job.
And while he doesn’t think the texts are a smoking gun proving Mr Johnson broke the rules over the cash, Lord Geidt said his report into the scandal would have been different if he’d known about them.

Business minister Paul Scully said Mr Johnson had engaged in "appropriate communication" with Lord Brownlow - who was supposed to be heading up a charitable trust to take over the maintenance of the No 11 flat - and that "nothing untoward" occurred.
Mr Scully told Times Radio: "Ministers get proposals all the time and what rightly happened was that this got pushed on to the Culture, Media and Sport Department (DCMS) where it sits.
"Lord Brownlow made his own approaches and it wouldn't have just gone to the Prime Minister, but the important thing is it's not gone ahead... so there's nothing untoward that's happening out of, you know, a few lines in a WhatsApp."