Big companies want to take over the processing of Medicare claims and assess eligibility for benefits as well as run the agency’s call centres and other functions, internal Health Department documents reveal.

The federal government is considering bringing in a private player to take over Medicare’s payment system but documents released under FOI laws show that big business is hungry for a much bigger chunk of the Medicare pie.

The department has been approached by private-sector players who want to take over claims processing, benefit assessment, call centres and registrations.

The documents were release after an FOI request by the Community and Public Sector Union, which is bitterly opposed to any outsourcing, fearing its members at Medicare’s parent department Human Services might lose their jobs.

There were also fears over the privacy implications of allowing the private sector or multinational corporations wide access to the medical and welfare records of millions of Australians.

The idea has been controversial since the Health Department called in August 2014 for expressions of interest from private players to take over Medicare, the Pharmaceutical Benefits Scheme and some Veterans Affairs benefits.

The government was forced to hose down what it called “alarmist exaggerations” that there was to be a “sell-off of Human Services” on the cards or that 20,000 public service jobs might be lost.  

But according to the internal Health Department documents, some of the firms jostling for the work are thinking much bigger than the department or its minister.

“We have had approaches from companies who are also interested in providing other related services such as registers, call centres and other processing,” one internal briefing note said.

“We really need to wait until we see what the commercial sector is offering and then make choices based on the benefits and risks of having a range of DHS services provided by a commercial operator.”

The union has told its members that the internal documents confirm at least some of its fears about the expressions of interest process.

“These documents reveal that the private companies that expressed interest in the work asked to take over more Medicare work than originally planned – and that the Department of Health were at least considering giving in to these requests,” a bulletin to union members at Human Services read.

“These issues raise significant doubts about the government’s assurances about Australia’s largest database of medical information staying inside the public service.”

The Health Minister’s office referred questions on Wednesday to the department office, which did not respond before deadline.

Fairfax Media revealed this year that companies from the US, Germany, Japan and Britain have approached the Commonwealth, interested in taking over the Medicare payment system.

Only three home-grown players – Eftpos, Australia Post and Telstra offshoot Stellar – are in the hunt to secure the massive contract if the government decides to go ahead with the privatisation.

But British services giant Serco, Japanese-US outfit Fuji-Xerox, German software behemoth SAP as well as American outsourcing powerhouse Accenture are all understood to be circling too.