A Liberal senator says thousands of low-income seniors aren't being told they're eligible for federal income subsidies of up to $560 a month, the Montreal Gazette reports.

Percy Downe said Statistics Canada figures from 2002 showed 134,775 seniors were eligible for the guaranteed income supplement but weren't receiving it, the Gazette reported from Ottawa on Thursday. In a letter to Auditor-General Sheila Fraser, the Prince Edward Island senator said the government puts more resources into tax collection than informing seniors about the supplement.

"Considering that the government spends huge amounts of money to ensure that Canadians pay their taxes, it should make an equal effort to ensure that it pays the money owed to citizens," Downe wrote on Jan. 13.

Downe suspects the actual number of seniors being shortchanged is much higher than the Statscan figures since the numbers were based on tax returns. Many low-income seniors don't file a return because they don't owe taxes.

But because they don't file, Downe says they aren't being told they may be eligible for the supplement.

While Fraser is not ruling out an audit of the program, she said her office will decide independently whether to investigate.

"I certainly share your view that the GIS program should be managed economically and efficiently," Fraser wrote in a reply to Downe on Wednesday.

"I have forwarded a copy of your letter to my staff responsible for audit work."

Mitch Bloom, an official at Social Development Canada, said his department has undertaken an aggressive effort to inform seniors about the supplement.

But he acknowledged the department is having trouble reaching some seniors, including the homeless, aboriginals and the mentally ill.

The guaranteed income supplement provides up to $560 a month on top of old age security pension payments, depending on a person's income and living arrangements.

For example, a single person must earn less than $13,464 to qualify. Seniors with incomes above $32,592 are not eligible.