Dominic Raab is being investigated over five fresh formal complaints about his conduct. Downing Street said Rishi Sunak has referred the new allegations to the senior lawyer conducting a bullying inquiry.
No 10 said the new accusations relate to the Deputy Prime Minister’s time at the Ministry of Justice (MoJ).
It takes the total number of complaints in Adam Tolley KC’s investigation to eight.
The Prime Minister’s spokesman declined to discuss the “extensive detail” of what period at the department the fresh allegations relate to, with Mr Raab currently on his second stint as Justice Secretary.
The official said: “I can confirm that the Prime Minister has now asked the investigator to include five further formal complaints relating to conduct at the Ministry of Justice as part of the ongoing investigation and in line with the existing terms of reference.”
Asked how the MP for Esher and Walton can remain in his Cabinet role considering the breadth of the allegations, the spokesman said: “We think it’s right there is an independent process, that the investigator looks into these claims thoroughly before coming to a view.”
The official would not put a timescale on when the investigation will be concluded, but said it is hoped to be finished “swiftly”.
The Prime Minister made Mr Raab Justice Secretary in October, reappointing him to the position he served in under Boris Johnson for a year until September.
The three complaints already under investigation related to Mr Raab’s time as foreign secretary and Brexit secretary, as well as his time at the MoJ.
He also held jobs in the department between 2015-2016 and 2017-2018.
Mr Raab has denied allegations of bullying and insisted he “behaved professionally at all times”.
The Prime Minister appointed Mr Tolley, a commercial and employment law specialist, to look into two initial formal complaints in November, but his inquiry has twice been expanded.
The lawyer needed to be brought in because the role of adviser on ministers’ interests has been empty since Lord Geidt’s resignation in June.
Labour has suggested Mr Raab should face suspension while the allegations are investigated.
A Labour spokesman said: “It’s pretty shocking that no action has been taken against the Justice Secretary given the allegations that there have been.
“Unfortunately, I think this is yet again the consequence of having a weak Prime Minister who has shown repeatedly on these issues a lack of willingness to act.
“The idea that Dominic Raab can continue in post with no consequence whilst there are these allegations around, I think most people would find pretty surprising.”