The government's leader in the Senate is under pressure to apologize for the actions of one of her former staffers, who leaked information about the travel expenses of Liberal senators.

But Conservative Senator Marjory LeBreton is standing by Jeffrey Kroeker, her one-time senior policy adviser, whose actions were ruled to be unethical by a Senate committee.

The issue dominated question period on Wednesday, with Liberal senators demanding an apology from LeBreton.

"Will you therefore show respect for your office and respect for this chamber and apologize," asked Liberal Senator James Cowan.

"I do not believe that I have to take lessons in ethics and integrity from people opposite. In my view, this incident is closed," LeBreton said.

Kroeker looked into the travel expenses of four senators and obtained hotel invoices containing confidential credit card information.

Kroeker then leaked those invoices to the media to promote stories about extravagant spending on the part of mainly Liberal senators.

The senators came under criticism for an attempted trip to Afghanistan on a fact-finding mission after stops in London, Rotterdam and Dubai. They were stranded in a Dubai hotel after military commanders told them it was too dangerous to continue. The entire trip cost close to $150,000, with $30,000 spent for the six days at the hotel.

The Senate Standing Committee on Internal Economy, Budgets and Administration investigated the incident and cleared the senators, saying there was no misuse of funds.

But the same Senate committee tabled a report finding Kroeker guilty of wrongdoing.

"Mr. Kroeker's conduct in gathering and disseminating the information was inappropriate and unethical," the committee reported.

Kroeker promoted

Since the incident, Kroeker has been promoted to a more senior position in another cabinet minister's office.

"I think it is deeply regrettable that, given the behaviour he engaged in, he has been given a promotion by this government," said Liberal Senator Sharon Carstairs.

LeBreton, who described Kroeker as a whistleblower, refuses to apologize for his actions.

"I have nothing to say to you or the CBC," she told CBC News.

On his Facebook website, Kroeker said "I stand by what I did for Canadian taxpayers and I do not feel that I did anything wrong in the slightest."

Liberal senators are now contemplating what to do next and may move to declare LeBreton in contempt of the chamber if she continues to reject their demands for an apology.