Pressure is already being ramped up on Dominic Raab following the sacking of Nadhim Zahawi.

Labour began turning its attention to Raab – one of Rishi Sunak's closest allies who has been the subject of bullying allegations – on Sunday, immediately after the prime minister acted following days of negative headlines about Conservative Party chair Zahawi's tax affairs.

It has been reported at least 24 civil servants are involved in formal bullying complaints against deputy prime minister Raab.

And following Zahawi's sacking, Labour's Andy Burnham said Sunak should suspend Raab until the investigation into his conduct is complete.

The mayor of Greater Manchester told Sky's Sophy Ridge On Sunday programme: "I think he should deal with the Dominic Raab situation in the way that I've described. That isn't going away.

"When ministers are subject to serious investigations like that, I think they should temporarily step aside from their roles. The Boris Johnson situation needs to be dealt with. Questions need clearing up but by failing to do that, they then dominate and that's the issue that I'm raising here."

Watch: Why has the PM sacked Nadhim Zahawi?

Bridget Phillipson, Labour's shadow education secretary, also weighed in following Zahawi’s sacking: "Despite the writing on the wall, the prime minister showed himself to be too weak to act.

"Rishi Sunak should have sacked Nadhim Zahawi a long time ago, just as he should have acted over Dominic Raab and Suella Braverman, but in his weakness he promoted them."

Read more: Boris Johnson claims UK would be 'gravitationally sucked into EU's orbit' under Labour

Zahawi was fired by Sunak for a "serious breach" of the Ministerial Code over his handling of his "personal financial arrangements and declarations", with reports saying he had to settle a £4.8m bill with HM Revenue & Customs. Zahawi had sought to present the settlement as following a "careless and not deliberate" error.

The Ministerial Code also states "harassing, bullying or other inappropriate or discriminating behaviour wherever it takes place is not consistent with the Ministerial Code and will not be tolerated" – meaning Raab's position will come under growing scrutiny.

The Guardian reported this week that the number of complainants is thought to be at least 24 and could exceed 30. Downing Street insisted on Thursday the number of formal allegations against Raab remained at eight but could not rule out that each complaint includes multiple accusers.

Raab has denied all allegations of bullying while under investigation by senior lawyer Adam Tolley.

Last week, he insisted he is "always mindful of the way I behave".

"I'm confident I behaved professionally throughout, and of course the Government takes a zero-tolerance approach to bullying," he told the BBC.