A Liberal senator whose housing expenses have been under scrutiny in recent months has put the Pembroke, Ont.-area house he calls his primary residence on the market.

Mac Harb was one of three senators who had their expense records referred to an external auditor after questions were raised about the legitimacy of their housing claims. It is expected that the results of those audits will be made public on Thursday after an internal Senate committee evaluates the findings.

Senators are entitled to collect up to $22,000 per year for the cost of living in Ottawa if their main residence is more than 100 kilometres away from Parliament Hill. Mr. Harb, a former Ottawa MP and city councillor who owns a residence in the city, has been claiming his house near Pembroke as his primary residence, allowing him to collect the stipend. That house, which is located less than 150 kilometres from Parliament Hill, was listed for sale about two weeks ago.

Independent Senator Patrick Brazeau and Conservative Senator Mike Duffy were also audited for their housing claims. Mr. Brazeau has said that his primary residence is located in Maniwaki, Que., but media reports have suggested he lives mainly in Gatineau, just across the river from Parliament Hill.

Mr. Duffy, who claims his PEI cottage as his primary residence but has lived in the Ottawa area for decades, voluntarily repaid about $90,000 in expenses this year, after saying he may have misunderstood the claim forms.

The housing audits, which were conducted by Deloitte, are expected to provide an analysis of the senators’ practices in claiming housing expenses. But it will be up to the Senate committee on internal economy, which handles Senate expense issues, to determine whether the claims were made improperly and whether or not the money should be paid back, a source familiar with the auditing process said.

If the committee determines that Mr. Harb and Mr. Brazeau were wrong to collect a stipend for their Ottawa-area houses, each could be on the hook for tens of thousands dollars, based on their publicly reported expense claims.

The Senate began making members’ expenses public in September, 2010, and Mr. Harb has claimed more than $42,000 in housing expenses since that time. If he claimed a similar amount during each of the 10 years he has been a senator, the total would amount to more than $160,000. Mr. Brazeau has claimed more than $38,000 in housing expenses since March, 2011, according to Senate records.

NDP MP Charlie Angus accused the government on Tuesday of failing to hold senators to account for their spending, citing a report that said Mr. Harb and Mr. Brazeau could be forced to pay back more than $130,000 in improper housing claims as a result of the audits. He said the RMCP should be called in to investigate the senators’ spending.

Liberal Senator George Furey introduced a motion on Tuesday that seeks to allow Mr. Brazeau back into the Senate to observe upcoming internal economy meetings. Mr. Brazeau, 38, was suspended from the Senate and removed from the Conservative caucus this year after he was charged with assault and sexual assault. He has pleaded not guilty.

A separate audit into Conservative Senator Pamela Wallin’s travel expenses is unlikely to be released at the same time as the others. Ms. Wallin’s audit is expected to be more complex because it involves poring over the details of her travel costs over a number of years, while the housing audits focus largely on lump-sum claims for housing stipends.

Marjory LeBreton, government header in the Senate, and Liberal opposition leader James Cowan have said the results of all four audits will be made public.

Both Ms. LeBreton and Mr. Cowan said on Tuesday that they hadn’t yet seen the audits.