Two Liberal MPs are calling on the only medical doctor in the Conservative caucus to oppose cuts to a program that provides health-care services to refugees, saying it is her "medical duty" to do so.

In an open letter to Conservative MP Kellie Leitch, Liberal MPs Hedy Fry and Carolyn Bennett say the cuts to the Interim Federal Health Program (IFHP) will result in "many refugee claimants being denied life-saving medical treatment, including prescription drugs for illnesses like diabetes and epilepsy, and necessary mental health services."

Prime Minister Stephen Harper defended the changes saying, "We are ensuring that all necessary health services are provided to refugee claimants," when questioned by reporters following an announcement on cleanup funding for Lake Winnipeg in Gimli, Man., on Thursday.

"At the same time, we are not providing services that are not available to the ordinary working Canadian," specified Harper.

But the Liberals say the cuts to IFHP will be downloaded to the provinces and charitable organizations, and won't actually save the government any money.

The open letter states it is incumbent on Leitch "to examine the evidence and not be blinded by ideology."

In a statement to CBC News, Leitch said the changes are "fair and necessary."

The Conservative MP said Canadians "do not want illegal immigrants and fraudulent refugee claimants to receive health-care benefits that are better than those of Canadians, including children and seniors."

Leitch, who represents the Ontario riding of Simcoe-Grey, referred to the open letter by the Liberals as an example of their "increasing desperation."

The changes have drawn criticism from Canada's medical community and leading health organizations since coming into effect on June 30.

On Tuesday, Liberal MP Kevin Lamoureux, the party's citizenship and immigration critic, said his party intends to propose a motion calling for an in-depth study of the impact of the cuts to IFHP once Parliament resumes in September.

Lamoureux wants the citizenship and immigration committee to hear from those involved, including health organizations and refugees, so the committee can come up with recommendations on how to reform the program.