A leading lawyers' group has sided with public servants who "rort" their workers' compensation entitlements, according to Public Service Minister Eric Abetz.

And the minister says reports that the big end of town was driving sweeping changes to the compo scheme were "false" and like a "half-baked union conspiracy theory".

Senator Abetz reacted angrily on Monday to The Canberra Times' report that national private sector companies had lobbied hard for changes to Comcare that would strip Commonwealth workers of some of their entitlements.

In a letter to the editor published on Wednesday the Tasmanian senator lashed out at public servants, who he accused of seeking "compensation payments for questionable 'treatments' such as week-long yoga retreats or grass cutting services".

But one of the nation's leading compensation lawyers dismissed the minister's attack as "polemical crap".

Changes to the Comcare scheme, introduced to Parliament by Senator Abetz, will make the scheme less generous and more attractive to private sector companies operating across Australia who are now eligible to join.

This newspaper reported that  key aspects of the reform were demanded by big business which was  keen to reap the savings of being insured by a national scheme, but feared its perceived generosity to workers would cost too much.

Comcare is a potentially attractive proposition for national employers who can make big savings by complying with just one national health and safety regime for all their sites across Australia, instead of a different authority for each state and territory.

But Senator Abetz, whose office refused to answer questions last month about private sector input into the bill, wrote that there was more consultation with public sector employers than with their counterparts in private enterprise.

"There was expansive consultation with unions, the human resources and the legal community as well as public sector employers. Indeed there was more consultation with that cohort than with private sector employers," the minister wrote.

Senator Abetz said his reforms would prevent repeats of the infamous sex-in-a-motel case.

"These reforms will also prevent compensation payments for questionable 'treatments' such as week-long yoga retreats or grass cutting services," he wrote.

"They will also prevent workers from claiming 'injuries' because they weren't able to access their favourite brand of soy latte during work hours.

"All of these things have been allowed to take place under the current system."

The minister also lashed out at the Australian Lawyers Alliance which has  been critical of the changes before Parliament.

"It is disappointing that the Australian Lawyers Alliance is taking the side of those who would seek to rort the current system, instead of considering the interests of honest workers and the taxpayers who must fund such rorts," Senator Abetz wrote.

But leading compensation barrister Allan Anforth said the minister's "intemperate" attacks showed that his reforms were politically motivated.

"These comments by the minister just go to confirm what a political exercise this is," the Canberra-based lawyer said.

"Nobody denies that there are things (about Comcare) that need to be fixed up, nobody.

"But when the minister comes out with polemical crap like this, that doesn't contribute to a balanced or reasonable debate."