ICAC Michael Riches told Sky News he intends to return to work “soon” following extended sick leave related to domestic violence allegations, but his return may be hampered by a new investigation into several “serious” allegations of “inappropriate behaviour” in his office by the Public Employment Commissioner.

It was reported yesterday by The Australian that new allegations of “inappropriate behaviour” had been levelled against Mr Riches by staff in the Office of the ICAC to the ICAC Inspector, while Mr Riches was investigated for the domestic violence allegations.

The NT Independent can now reveal that at least two women in the office have also filed complaints against Mr Riches internally, while sources said some employees are refusing to show up to work if Mr Riches returns on Monday.

The Chief Minister’s Office confirmed that allegations “relating to employment-related matters” were raised by staff during ICAC Inspector Bruce McClintock’s investigation into alleged misconduct by Mr Riches, following the domestic violence allegations made by his estranged wife being made public.

While Mr McClintock cleared Mr Riches of improper conduct related to the domestic violence allegations, including paying his wife $20,000 to drop a DVO application, he made no conclusion on the DV matter itself, and the workplace allegations were not previously reported in the summary of Mr McClintock’s investigation.

“The ICAC Inspector determined that these matters were outside the scope of his enquiries and they should be referred to the Commissioner for Public Employment which has been done,” the Chief Minister’s Office said in a statement.

Public Employment Commissioner Nicole Hurwood said on Wednesday that she was investigating “a series of matters regarding alleged inappropriate workplace behaviour within the Office of the ICAC”.

“Given the serious nature of the matters and the high-profile role of the individuals involved, I am securing the services of an appropriately qualified and experienced investigator from interstate to undertake the investigations on my behalf,” Ms Hurwood said.

“As is the usual case for matters of this nature, to protect the privacy and confidentiality of the individuals involved, no further comment will be made on the matter.”

Mr Riches, who refused to provide details of the allegations of domestic violence on the record to this masthead or whether they were fully disclosed, told the national broadsheet on Tuesday that he was unaware of the nature of the new workplace allegations raised with the Inspector.

“If there are human resource matters within my office to be addressed, I want them addressed,” he said.

The NT Independent sent questions to Mr Riches on Wednesday seeking comment about the female staff members filing internal complaints.

“I do not know what the allegations are,” he said in an email. “I have always acted with the utmost professionalism toward all of my staff, and any suggestion to the contrary is outrageous.”

Internal messages seen by the NT Independent show some female staff members feel distressed about Mr Riches’s possible return to the office, while sources have said a number of staff intend to walk out if Mr Riches returns on Monday, which he reportedly told some staff would be the day of his return.

Acting ICAC Naomi Loudon was sworn in last Tuesday and fronted Estimates that day, telling the parliamentary committee that Mr Riches was not in contact with the office and that she was providing “leadership” to staff who had been through a “tumultuous time”.

“Commissioner Riches is on a period of personal leave, and as I understand it, he is not having contact with our office,” she told the Estimates committee.

Ms Loudon declined to comment yesterday on whether her conflict of interest in the Labor election rorts investigation was related to her personal friendship with a former Labor staffer connected to one of the subjects of a second report that was to be finalised by the end of the month. The second part of the Operation Jupiter report remains in limbo presently. Ms Loudon also declined to comment yesterday on compromising photos allegedly depicting her in an intoxicated state at a Darwin bar that were viewed by office staff last year.

Mr Riches told Sky News on Tuesday that he was looking “forward to returning to the office as soon as I can”, after the media outlet reported a two-page statement that he provided only to them.

The summary of Mr McClintock’s investigation report will be tabled in Parliament on Thursday.