(This story has been updated. Please see Corrections note below.)

Conservative Yukon Senator Daniel Lang and his policy adviser were forced to fend off allegations of workplace harassment, multiple senior Senate sources tell CBC News.

The Senate's human resources department became involved after a complaint about Lang's alleged treatment of a parliamentary staffer earlier this year, the sources said.

The Senate would not confirm the internal review, or identify the nature of the complaint.

"The integrity of any complaint-based human resources process is dependent on confidentiality being maintained. For this reason, the Senate does not disclose information of this nature," Senate spokesperson Jacqui Delaney said.

Lang, appointed by former prime minister Stephen Harper in 2009, declined requests for an interview but his policy adviser, Naresh Raghubeer, provided a statement Thursday quoting the senator.

"I don't know where you heard this, but neither my office nor I are currently subject to any administrative review," the statement sent to CBC News said.

Lang contacted CBC News late Thursday with a further statement.

"This report by the CBC is false," it said. "My office is not subject to a harassment probe by the Senate. Neither I nor anyone in my office is in breach of Senate policy related to workplace harassment or any other Senate policy."

This is not the first time Lang and Raghubeer have dealt with allegations about workplace harassment. An earlier complainant, in 2016, ultimately transferred to another job on Parliament Hill.

After this story was first published, Raghubeer contacted CBC News again to say the 2016 complaint was investigated by an outside agency and the complaint was deemed to be unfounded.

"There was a workplace complaint against me in 2016 that was fully investigated by an outside independent investigator and found to be 'utterly baseless,'" Raghubeer said in a statement Thursday evening. "Senate harassment policy strictly prohibits me from commenting on this matter so as to respect the privacy of the complainant.

"I can confirm that legal fees were provided as part of the employer's indemnification policy, and as the complaint was deemed 'unfounded,' the Senate assumed the responsibility for the legal costs incurred.

His lawyer, Paul Champ, on Friday sent CBC News a letter from the Senate confirming that the external investigation deemed the complaint to be unfounded. Champ added "there are no other harassment complaints against Mr. Raghubeer, pending or otherwise."

Senate officials privately describe the complaints as being about bullying and intimidation, including screaming and belittling in front of other senators and staff.

The sources spoke to CBC News on the condition of anonymity because they were not authorized to discuss the matter with reporters and/or they feared retribution from their superiors.

However, the confidential report by the external investigator, later shared with CBC News, repeatedly found the allegations by the complainant were examples of "minor workplace friction or discord between colleagues" and did "not fall into the category of behaviours that could potentially ... be seen as triggering the harassment/abuse of authority" section of the Senate's anti-harassment policy.

"There are no villains in this situation, these are simply two colleagues in a very small office environment who did not mesh very well. How and why this kind of fact situation necessitated such a formal investigation process may be a good discussion point for those overseeing such matters within the Senate," the investigator wrote.

Lang gets Senate funds for legal costs

Lang and Raghubeer have applied for and received approval for Senate funds to cover legal expenses associated with the harassment allegations.

In total, the Senate's internal economy committee has approved more than $28,000 from the legal indemnification fund for Lang and his staff since the Yukon senator was first appointed, according to Michel Patrice, the Senate's law clerk and parliamentary counsel.

The Senate would not specify how of much that $28,000 was allocated to deal with the harassment claims.

"We can confirm that both Senator Lang and a member of his office have received disbursement of legal fees in accordance with the Senate's policy on legal fees and indemnification," Delaney said in an email.

Lang's office declined to comment on his use of Senate legal funds.

Senate headaches

This is the latest headache Senate leaders have faced in only a few short months.

In March, in a far more serious case, the Senate ethics officer found Independent Senator Don Meredith breached two sections of the Red Chamber's ethics code for having a sexual relationship with a teenage girl. The Senate's ethics committee is reviewing Lyse Ricard's report and is currently deciding on how to sanction Meredith for his behaviour.

Some members of the Senate are so determined to expel Meredith that they have tasked the Senate's law clerk with combing through the Constitution in search of a line they can use to force the Toronto-area senator to step aside for good.

Conservative Senator Lynn Beyak also ignited a firestorm of criticism after she defended the residential school system, telling her colleagues she was disappointed the Truth and Reconciliation Commission didn't "focus on the good" done in these institutions. Interim Conservative Leader Rona Ambrose ultimately removed the Ontario senator from the Aboriginal peoples committee after Beyak doubled down on her remarks.

Peter Harder, the government's representative in the Senate, recently conceded the controversies have been a "kick in the gut" that has temporarily derailed efforts by the Senate to improve its standing among Canadians.