The Liberals are preparing to block a Conservative attempt to question staff from the Prime Minister's Office following an alleged leak about the assisted-dying bill.

A spokesman for Prime Minister Justin Trudeau says Liberals on the procedure and House affairs committee will vote against a series of motions to invite Kate Purchase, Trudeau's director of communications, and Katie Telford, his chief of staff, to be questioned about an April 14 report in the Globe and Mail. The story described some of the elements of the government's assisted-dying legislation before it was tabled in Parliament.

The Liberals outnumber opposition MPs on the committee, which next meets on Thursday.

"Since the opposition has been unable to offer any evidence that there even was a premature disclosure of the bill during six different committee meetings, the government members on the committee have decided to oppose any motion that randomly calls anyone as a part of their fishing expedition," Cameron Ahmad wrote in an email to CTV News.

That also refers to the motions to call Health Minister Jane Philpott and Government House Leader Dominic LeBlanc, which were presented by Conservative MP Blake Richards at the same time as the motions to call Purchase and Telford.

The Conservatives complain the bill was leaked in a breach of parliamentary privilege, since bills are supposed to be secret until they're presented in the House. The Liberals say it's not clear there was a leak and argue the Globe reporter could have made a series of educated guesses about the bill's content. The Globe story cites a source who provided the information under cover of anonymity.

Richards questioned why the Prime Minister’s Office was speaking on behalf of the Liberal MPs on the committee.

"The fact that it's being directed by the PMO certainly would seem to go counter to what their promises are, [that they would] let committees operate independently," he said. "That would certainly be a concern to me."

Richards says he still hopes the government will produce the list of civil servants and political staffers who would have seen the bill before it was tabled in the House.

"Obviously the Liberals have the majority on the committee. If they try to sweep this under the rug... I guess they have the votes on the committee to do so. We're hopeful that they will see better than that and choose to do the job that we've been tasked to do," he said.

Both Liberal and Conservative MPs have mused about calling the reporter to committee to answer questions, although Ahmad, Trudeau's spokesman, later said the government doesn't think journalists should be called upon to disclose their sources.

Justice Minister Jody Wilson-Raybould spent an hour last week answering questions from committee members. She and Philpott are the lead ministers on the assisted dying file.