MPs are vowing that the upcoming prorogation of Parliament won’t impede efforts to improve transparency around political spending in the wake of an expense scandal that rocked Ottawa in recent months.

MPs from the Conservatives, Liberals and NDP briefly returned to Parliament Hill on Sunday for what should have been a closed-door meeting of the Tory-chaired Procedure and House Affairs Committee, where they were slated to discuss the need for greater transparency around the expenses of MPs and Senators.

But within minutes of the meeting’s scheduled start, an NDP motion to open up the in-camera meeting was approved and the doors thrown open to the public.

About an hour into the meeting, the committee also unanimously agreed that they should seek Commons approval on continuing their work once the House returns later this fall.

MPs were slated to reconvene next week on Sept. 16, but Prime Minister Stephen Harper announced he would prorogued the upcoming session last month, saying there was a need to refresh legislation. The House is now expected back in mid-October.

The move quashes all government business, including the committee’s work, but Sunday’s vote publicly commits Tory MPs to resume discussions on the matter as soon as possible.

Meanwhile, Tory committee chair Joe Preston said Sunday some clerks and other staffers would continue to work ahead on planning and research linked to spending transparency.

The committee agreed to table a report on the topic on Dec. 2.

NDP House Leader Nathan Cullen said it was important to push on with the topic since the public has been “outraged” by the recent spending scandal.

"If you allow the Prime Minister to change the channel, he'll just slip under the rug on this one," he told reporters in Ottawa.

His committee co-members agreed that the issue must be dealt with in a timely manner.

“With recent events in the Senate this public is, I think, rightfully so clamouring for more transparency and accountability. They want to make sure that their taxpayers' dollars are being spent wisely and not abused," said Tory MP Tom Lukiwski.

"They've seen what appears to be some pretty flagrant abuses in the Senate with tax dollars and I think the public is rightfully outraged."

In June, toward the end of the last session of Parliament, an NDP motion calling for a committee process to examine transparency reforms won unanimous approval.

The motion included potentially doing away with the secretive Board of Internal Economy, whose meeting are always held behind closed doors.

It also requires the committee to conduct hearings on how to replace the Board of Internal Economy and boost oversight of MPs’ salaries, expenses and office budgets.

Cullen said Sunday the New Democrats want to implement a system that applied to all members of parliament consistently, to be overseen by an independent body.

"So MPs are not policing themselves," he said. "That's something that has to be done away with. None of this voluntary, one-off kind of procedure."

Before Sunday’s meeting was thrown open, Cullen had said it was "ironic" the Conservatives were holding an in-camera meeting on transparency and accountability.

"It's not a good first step on the path toward transparency that Parliament has committed itself to," he said.

Meanwhile, the Liberal Party has committed to voluntarily posting the travel and hospitality expenses off all senators and MPs online beginning Sept. 18.

"We're doing this to set the bar for other parties to come onboard," Liberal Leader Justin Trudeau told CTV's Question Period.

Trudeau introduced four motions in June that would force MPs to post their expenses online, and allow the public to scrutinize how elected officials spend taxpayers’ money.

While the Conservatives supported the motions, which would have required unanimous consent in order to pass, the NDP voted against them.

"For right now, we're going to lead on our own," Trudeau said.

The ongoing expense scandal -- which saw four senators ordered to payback hundreds of thousands worth of claims for inappropriate housing and travel expenses -- dominated the last session of Parliament.

The RCMP has been called into investigate the questionable claims of Tory-appointed Senators Mike Duffy, Pamela Wallin and Patrick Brazeau, as well as ex-Liberal Mac Harb, who has since resigned from the Upper Chamber. Auditor General Michael Ferguson has also committed to probing the expenses of all senators.

"Certainly this controversy is not pleasant," James Cowan, the Liberal Leader in the Senate, told CTV’s Question Period Sunday.

"There are plenty of snide remarks and some more direct jabs about the behaviour of these four senators and a sense that maybe there are other senators doing the same thing. I don’t believe there are. We'll get to the bottom of this."