The Conservative government is again showing contempt for Parliament by refusing to release key information on the impact of its latest budget, says the NDP.

MPs are set to begin voting this week on the highly contentious budget implementation bill, but the Harper government won't say how many civil servants or what programs and services will be cut as a result of the omnibus bill.

"Essentially the government is requiring members of Parliament to vote blind on the legislation coming forward," NDP House leader Nathan Cullen argued Monday.

Cullen is asking the Speaker of the House of Commons to rule that the government has breached MPs' collective privileges by withholding data requested by Kevin Page, the independent parliamentary budget officer.

Prime Minister Stephen Harper created the PBO and appointed Page as one his government's first acts in 2006, with the express goal of providing independent information to MPs about budgeting issues. The measure was part of the Conservatives' vaunted Federal Accountability Act.

But when Page asked for information on cuts to the civil service that will result from this year's budget, he was flatly refused.

The clerk of the Privy Council, the bureaucracy that supports the Prime Minister's Office, subsequently wrote that collective bargaining agreements with various public-sector unions prevent federal departments from releasing the information on staff and service cuts until all staff have been notified.

The unions say they have no concerns about releasing the information — in fact they'd like it made public, as long as individual employees are not named.

"The government doesn't deny that these numbers exist. The numbers do exist," Cullen said in an interview, noting the unions' agreement that they be released.

"This means it's the first time in Conservative history where they're defending a collective agreement where the union says 'don't worry about it, we're good'."

He is asking Speaker Andrew Scheer to find that the government is breaking the rules of Parliament and hampering the ability of MPs to perform their central role: holding governments to account.

"If the House cannot hold the government of the day to account, then why have the House at all?" Cullen asked in the Commons.

"This isn't a right-left issue. This is right and wrong."

Cullen asked that Scheer rule on the matter as quickly as possible because voting on Bill C-38, the omnibus budget bill, begins this week.

Peter Van Loan, the government House leader, noted the bill was introduced on April 26 and the NDP is making its last-ditch pitch for transparency only now — "so (Cullen) is very late to make this argument."

Van Loan also said the kind of detailed information Cullen is seeking usually gets approval in appropriations bills, not budget implementation bills.

"I think that is the appropriate point for him to raise his questions," said Van Loan.

The Harper government was found in contempt of Parliament for withholding information in March 2011 — an unprecedented vote that helped spark that year's election — and Cullen argues the latest refusal to provide budget information is a new breach of privilege and again puts the government in contempt.