Government whip Phillip Ruddock has defended a new taxpayer-funded unit set up to advise coalition members and help them respond to opposition criticism.

Labor has been seeking details about the unit, known as the Coalition Advisory Service.

A list of "government personal positions" released through the estimates process shows the CAS reports to Mr Ruddock and has an allocation of 10 staff positions.

Labor senator John Faulkner has called for the CAS to be made the responsibility of a minister, so it can be properly scrutinised by a Senate estimates committee.

Mr Ruddock said the service - described as a "dirt unit" by the opposition - had a legitimate role and previous governments had set up similar bodies.

"Members of parliament come, in many cases, without a great deal of background and experience in politics and running political offices that have to serve the needs of a constituency," he told AAP on Thursday.

"You need to have a basis on which you do try to service their needs."

He said the service's staff had a range of backgrounds in policy, training, media and running electorate and ministerial offices.

Asked whether its role was to dig up background on Labor MPs, Mr Ruddock said: "I would certainly expect that the unit would collect information about what is being said about me (as an MP), so I could reply."

He said such operations had been "part and parcel of the political process over a long period of time".

He did not believe the Liberal party should cover the cost of the service.

Senator Faulkner told an estimates hearing late last year he hoped the government was not trying to avoid accountability by putting Mr Ruddock, rather than a minister, in charge of the unit.