OTTAWA - Parliament's upper chamber has been swept up in a wave of acrimony and turmoil over a spate of forced Tory resignations from Senate committees.

The Conservatives say the musical chairs in committees is their prerogative and simply administrative. The Liberals say it's a case of a crackdown on independent-minded senators by Prime Minister Stephen Harper's office.

The latest to announce his resignation is Senator Michael Meighen, who told his colleagues on the security and defence committee late Monday that he has been told to resign as vice-chair. Meighen had served on the high-profile and prolific committee since its inception in 2001.

"I had a conversation with the leader of the government in the Senate, who asked me if I would tender my resignation," Meighen told the committee.

"I have always been a loyalist to my party. I expressed my amazement to her. I am obviously not going to recount the nature of our conversation, but I indicated I was extremely disappointed."

Meighen had contradicted the government last fall when he defended a committee trip to the Middle East. The senators ran up a hefty tab in Dubai when they were unable to get into Afghanistan, spurring the Tories to accuse the committee of wasting taxpayers' money on a junket and demanding an internal investigation.

The senator said in an interview he doubts that was a reason for the requested resignation, which was explained to him as "administrative." But Meighen says he remains perplexed.

"I think for some reason they seem to be quite cross at me," Meighen said. "I was not given any example of some heinous crime that I had committed, or that my work was not of the best quality. I have no idea."

Meighen's departure follows that of Tory luminary Hugh Segal, who announced he had been instructed to resign as chairman of the foreign affairs committee. Senator Donald Oliver was asked to resign his chairmanship of the legal and constitutional affairs committee to replace Segal, but was blocked by angry Liberal senators.

The government leader in the Senate, Marjory LeBreton, dismissed the allegation that the senators had been moved because of anything they had said or done on the committees.

"We were simply changing the vice-chair, and it was a decision of the caucus and of the leadership, and that's as far as I'm going to go on the reason why," LeBreton said of Meighen's resignation.

She also derided the notion that she needed to get permission from the Liberals, who hold a majority of seats in the Senate, over changes the government wants there.

"It never occurred to any of us that the Liberals would want to interfere in our caucus matters. This is a caucus matter. This is what's wrong with this place, this kind of closed little society with its precedents," LeBreton said in an interview Tuesday.

Her Liberal counterpart, Senator Celine Hervieux-Payette, said there's a time-honoured tradition of cordiality and consultation when deciding the helms of committees. She added that mid-session changes are unusual for committees that are generally ensconced in studies and reports.

"We are independent in this place. This is why we're appointed, to serve the Canadian population and not the interests of a party," said Hervieux-Payette. "We're appalled."

The Liberals sent a shot across the bow of the Tories by at least temporarily ignoring LeBreton's picks for committee chairs and vice-chairs.

Meighen's former job as vice-chair of the national security and defence committee was filled by a Progressive Conservative, Norm Atkins. LeBreton responded in the skirmish by removing all Tory members from the committee until further notice.