Dominic Raab insisted he “always acted professionally” despite increasing allegations of bullying.
The deputy prime minister told Sky News on Thursday he looked forward to dealing with the allegations “fully and transparently”.
It comes after the BBC reported that civil servants who worked for Mr Raab were preparing to file formal complaints about bullying.
Rishi Sunak has appointed senior lawyer Adam Tolley KC to investigate two formal complaints filed last week over Mr Raab’s conduct, but number 10 says the prime minister still has full confidence in him.
And Mr Raab also insisted it was “perfectly legitimate” and in line with guidelines for the use of his personal mobile phone for certain business matters, after Information evening made allegations that he used his personal e-mail address for government affairs in two different departments.
Asked by Sky News whether he had been told senior officials who worked closely with him had made complaints, Mr Raab replied: “I have always behaved professionally.
“And that’s me when the complaint came in a few days ago, the first complaint against me since I’ve been a minister since 2015 called for an independent investigation and I look forward to dealing with it fully and transparently rather than dealing with anonymous comments in media”.
When asked about the allegations about his mobile phone, he replied: “I have always followed the ministerial code, including the use of my iPhone.”
He said he was “always careful to protect the integrity of any communications” he has.
Asked how this is not a violation of the ministerial code, the deputy prime minister replied: “It’s very clear, I consulted on this matter. I’m sure about that”.
Investigated on reports that senior civil servants told him not to use his personal phone for government affairs, Mr Raab dismissed the claims as “anonymous speculation”.
He added that he “always took advice” on how to protect the integrity of communications, and when asked why he used his personal phone for certain purposes, he replied that it was “totally legitimate and in line with our guidelines.”
“I am confident that I have not broken the ministerial code in any way you claim,” Raab said.
He previously told MPs he would be “thoroughly involved” in his investigation and looked forward to “transparently addressing” the complaints.