How govt will pay for its research fund

Labor has slammed the federal government's medical research fund as a "cruel hoax", insisting the savings measures that will be used to pay for the fund have no hope of getting through parliament.

In response to a Senate estimates question on notice, the government has revealed 27 areas where it has found savings to pay for its $20 billion Medical Research Future Fund.

It includes $1.8 billion from changes to the way the government will fund public hospitals, along with $2.3 million from cuts to the World Health Organisation.

Opposition health spokeswoman Catherine King says the list reveals the fund is a "cruel hoax" on the medical community.

"These cuts include the $5 hike in prescriptions, and changes to the PBS and Medicare safety nets, all of which the government now admits have no hope of getting through the Senate but still count as savings," she told AAP on Wednesday.

Labor was also concerned the fund could be used to pay for coalition election projects, with no independent oversight of its distributions.

Health Minister Sussan Ley has conceded the $5 co-payment for prescription drugs does not have the support of the Senate crossbench.

But she's insisted that although she won't be putting the measure to the Senate, she won't be taking it off the table until equivalent savings are found elsewhere.