Liberal leader Michael Ignatieff has urged Prime Minister Stephen Harper to adopt a cap-and-trade system with hard caps and impose legal limits on prorogation in the next session of Parliament.

In an open letter to the prime minister, Ignatieff called for a special committee to review prorogation.

"Mr. Harper sacrificed his entire legislative agenda simply to avoid the kind of accountability and transparency he once promised to deliver," Ignatieff said. "That's why our party has come forward with a proposal to place reasonable and responsible limits on the Prime Minister's ability to request a prorogation, and limits on the overall impact of prorogation."

Ignatieff also put forward a number of Liberal initiatives from the party's recent roundtables, including:

• Encouraging investment in start-up businesses

• Reform the Canadian Pension Plan and provide support for at-risk private pensions

• Call for an investigation into missing Aboriginal women in the Prairies

• More support for veterans with post-traumatic stress disorder

Harper had invited the Liberals to outline their priorities for the next session of the minority Parliament.

"Over the past month, Liberals have hosted 24 public hearings that have produced a wealth of substantial policy proposals from Canadians of all political stripes," Ignatieff said. "We're putting forward a number of these proposals to provide the basis for a productive session of Parliament – assuming that Mr. Harper is interested in making our minority Parliament work."

Ignatieff is due to return to Ottawa Tuesday, where the Liberals have held caucus despite the prorogation.

Parliament is scheduled to resume March 3.

Since Harper made the move to prorogue Parliament in late December, his party has tumbled in polls, but still has a slight lead on the Liberals.