Ontario's opposition parties joined forces Thursday to demand Labour Minister Peter Fonseca resign for not investigating complaints by two women employed by Liberal MP Ruby Dhalla's family.

Dhalla, the MP for Brampton-Springdale, has denied allegations made by two live-in caregivers that she withheld their passports and paid them only a fraction of the minimum wage.

Magdalene Gordo, 31, and Richelyn Tongson, 37, say they were hired in early 2008 to work in Dhalla's family home in Mississauga, Ont., to care for her mother, Tavinder Dhalla.

The women told their stories to Fonseca and Education Minister Kathleen Wynne during a roundtable discussion last month, and were advised to call a toll-free hotline that wasn't even operational until the next week.

The Progressive Conservatives and New Democrats accused the two ministers of staying quiet because the complaints involved a prominent Liberal MP. Fonseca's role as labour minister demands that he resign for failing to do his job, they said.

"Those caregivers deserve a labour minister who is up to the job of protecting their rights, not one who casually dismisses their concerns by offering up a toll-free number," complained NDP Leader Andrea Horwath.

"His conduct is shameful. It's unbecoming of a minister of the Crown. It is time for him to go."

Interim Opposition leader Bob Runciman accused Fonseca of "incompetence and a lack of moral fibre" for not following up on the complaints he had personally heard about Dhalla.

"Your negligence, your failure to act, raises serious questions about a deliberate coverup," Runciman said in the legislature.

The Tories and NDP spent virtually the entire question period Thursday demanding Fonseca step aside while an investigation is conducted into how the complaints by the Dhalla family caregivers were handled.

Federal program at fault, says Fonseca

Fonseca said his job was to tell the women how to have their complaints addressed, not to interfere in any one case, and he again blamed the federal government's Live-In Caregiver program for foreign workers.

"We have heard many stories of abuse from many, many caregivers," Fonseca told the legislature.

"Most of the allegations stem back to a flawed, broken federal program."

The opposition accused Premier Dalton McGuinty of ducking question period for the second day in a row Thursday rather than face questions about Dhalla, calling him a "coward."

McGuinty was on the defensive when he faced media scrutiny at a Toronto-area school Thursday, but said both Fonseca and Wynne acted appropriately.

The premier lashed out at the opposition parties and reporters for focusing on the allegations against Dhalla when the ministers heard about 30 similar stories from caregivers, and said the women involved also had a "responsibility" if they wanted to pursue the matter.

"I know the opposition yesterday [Wednesday] demanded that Miss Dhalla be jailed," complained McGuinty.

"I just think that's entirely inappropriate. I think we have due process."

The Dhalla controversy also reopened the battle between the Ontario Liberals and the federal Conservatives after months of detente that saw unprecedented co-operation between the two former warring governments, including an agreement to harmonize the provincial sales tax with the GST.

Fonseca has repeatedly tried to blame the concerns raised by foreign caregivers on federal Immigration Minister Jason Kenny for problems with the program that brings in the workers to Canada.

The Conservatives used question period in Parliament on Wednesday to take retaliatory shots at Fonseca and suggested he wasn't enforcing provincial labour laws to protect Dhalla, a fellow Liberal.

Dhalla gave up her post as Liberal multiculturalism critic Wednesday to fight to clear her name and said she wasn't involved in hiring or supervising the caregivers, and has no knowledge of details regarding them.