OTTAWA - Ruby Dhalla is being called to answer claims of domestic worker abuse before a committee of MPs as the Liberals accuse the Conservatives of "lynch-mob" political tactics.

Dhalla has resigned as Liberal multiculturalism critic and says she'll fight to clear her name after two foreign workers accused her family of mistreatment.

She has denied any wrongdoing and says she was not involved in hiring or supervising the workers.

Dhalla said in a statement that she is "saddened and troubled" by the claims. She has asked the independent ethics commissioner to investigate.

Two caregivers who worked in the Dhalla home in Mississauga, Ont. last year say they were asked to do extra chores - from cleaning the family's chiropractic clinics to washing cars - and that they had trouble getting paid.

Magdalene Gordo, 31, and Richelyn Tongson, 37, say their passports were also illegally withheld. They had been hired to care for Dhalla's mother, Tavinder, in the home they share.

Both caregivers have also been invited to immigration committee hearings as early as next Tuesday.

"Of course it's a partisan tactic," Liberal MP Bob Rae said of the move.

"It's a feeding frenzy and I think we should put it in perspective. We're deeply fairness and justice for caregivers. And if there's an investigation that's required, let it take place. But don't turn it into a political lynch mob."

David Tilson, Conservative chair of the immigration committee, bristled at suggestions the Harper government is making political hay with Dhalla's troubles.

"We're studying the topic of migrant workers," he said, noting the committee's agenda was set before the Dhalla controversy erupted.

"We want to know...can the law be improved?

"It's not just nannies," who regularly complain their rights are violated by unscrupulous employers, Tilson said. "It's others."

The federal Live-In Caregiver Program has come under particular scrutiny for potential abuse, however.

A committee report tabled Wednesday in Parliament found the program "places the live-in caregiver in a disadvantaged position, dependent on her employment for more than her livelihood."

Such "vulnerable" foreign workers applying for permanent residency in Canada must work 24 months in the program during a three-year period.

But due to the system's slow processing times, caregivers who switch employers - for any reason - are hard-pressed to legally meet the 24-month quota.

"Since enforcing their rights could potentially mean getting fired and being unable to complete the two-year employment requirement for permanent residence, caregivers are almost always willing to tolerate abuse from the employer," said the report.

It recommends allowing caregivers to apply for an extension of up to a year to complete their 24-month employment period.

Canada had more than 200,000 temporary foreign workers in 2007.

Executive director Agatha Mason of Intercede, a Toronto agency that helps domestic workers, called Ruby Dhalla on behalf of Tongson. The caregiver, who worked for the Dhalla family for more than three months last year, complained that Dhalla took her passport and other documents to complete paperwork needed for federal approval of the placement. Weeks passed and the documents were not returned.

Mason told Dhalla to give Tongson her passport back within 24 hours or she would call police.

Mason said Thursday she didn't know at the time that she was dealing with a Liberal MP.

"It's possible she was busy and didn't get around to handing (the passport) back. But the caregiver has a different story."

Dhalla has denied seizing anyone's passport.

Mason says politicians of all stripes have for years ignored hundreds of complaints from live-in nannies and caregivers - most of them women.

She sees more than 120 clients a month, she said. More than half arrive to report rights violations, overwork, breached contracts and poor treatment.

"There are some good employers. But there are a lot of complaints from caregivers who say they're cooking, they're cleaning, they're servants at the end of the day."

Many have left their own children behind in the Philippines, Africa or Asia. Mason's clients hail from 21 different countries.

Some toil for three to five years and still don't attain the precious residency status that would allow them to bring their families to Canada, she said.

"Our stand has always been: why not let people come in as landed immigrants?"

Instead, the program as it works now essentially boils down to: "You can come here, look after our children, look after our elderly. But when we no longer need you, you have to prove to us that you're worthy to stay among us. And I think it's a shame."

The Conservatives have pointedly raised the accusations against Dhalla in the House of Commons the last two days.