WINNIPEG -- Manitoba's opposition parties are calling for an inquiry after Premier Greg Selinger admitted he knew for months that a cabinet minister misled the legislature.

Selinger told The Canadian Press he knew early on that former minister Christine Melnick had likely misled the chamber in the spring of 2012, but he did not go public with the knowledge.

Manitoba's ombudsman found an assistant deputy minister was following Melnick's direction when he sent out a controversial email inviting immigration agencies to a politically charged debate in the provincial legislature.

Melnick denied being behind the email at the time.

Conservative Leader Brian Pallister says Selinger should have corrected the record as soon as he found out and should throw Melnick out of caucus.

Both Pallister and lone Liberal MLA Jon Gerrard say Selinger should appoint a legislative committee to look into the controversy.