The Human Services Minister, Chris Bowen, said the changes were necessary to deal with a greater demand for more complex social services as the population aged.

''Our current service delivery structure is not up to scratch to meet these objectives,'' he told the National Press Club.

Private information that each agency currently holds on individuals would be shared, but only if a person consents.

''This is not an Australia Card, and we will not be merging agency databases,'' he said.

''We are bringing IT platforms together, not information itself. No more information will be shared unless the individual concerned asks us to share the information.''

The Child Support Agency and the disability service organisation CRS Australia are under the one roof.

After a successful trial on the NSW South Coast, Mr Bowen promised that by the end of 2010, there would be 20 more single offices around Australia and 40 more by 2012.

Each office will house Medicare, Centrelink, Child Support Agency, and CRS Australia.

In addition, a single website will be established by 2010 and there will be a single phone number to access any service within the portfolio.

''If we were redesigning the system from scratch, this kind of idea would probably seem obvious,'' Mr Bowen said.

By 2013, all transactions required will be able to be done over the internet, although using the web will only be an option.

''We are not forcing - and we will never force - people online,'' he said.

To facilitate the changes, Medicare and Centrelink will move under the Human Services departmental umbrella.