OTTAWA -- Conservative finance critic Pierre Poilievre says he'll filibuster the government's budget until the Liberals agree to further investigation of the SNC-Lavalin affair.

As the Official Opposition's spokesman on the budget, Poilievre can talk about it in Parliament for as long as he likes.

He plans to use that privilege to pressure Prime Minister Justin Trudeau to end what Poilievre calls a coverup.

The Ottawa-area MP says he'll end his speech only when the government agrees to have more witnesses testify on the pressure former attorney general Jody Wilson-Raybould felt to help SNC-Lavalin avoid a criminal prosecution over its allegedly corrupt dealings in Libya.

He wants senior members of Trudeau's staff and Trudeau himself to testify to the House of Commons justice committee.

The Conservatives used procedural tactics two weeks ago to force more than 250 separate votes on spending plans, using the round-the-clock session in the Commons to draw more attention to the SNC-Lavalin affair as well.