OTTAWA - Interim Liberal Leader Bob Rae wants an investigation into what he calls spending irregularities in the campaign of Intergovernmental Affairs Minister Peter Penashue during the last federal election.

In a letter to the Commissioner of Canada Elections, Rae requests a formal probe into a number of questionable transactions by Penashue's campaign in the riding of Labrador during the 2011 election.

Penashue has blamed rookie mistakes and says he's working with Elections Canada after spending thousands of dollars more than the legal limit in the campaign.

An Elections Canada review showed Penashue spent $4,000 over his limit of just under $84,500.

And CBC News has cited documents alleging he also took thousands of dollars in free flights around his sprawling Labrador riding.

Rae also wants the commissioner to determine whether a $25,000 loan Penashue received from the Innu Development Limited Partnership came with a commercial rate of interest as required under the rules.

Rae says the financial dealings could affect the vote's outcome, given that Penashue won by just 79 votes.