Labor has accused the treasurer, Scott Morrison, of preparing to back down on a key election promise after reports he may water down changes designed to make superannuation less generous as a tax minimisation strategy.

On Friday, the Australian Financial Review reported Morrison was considering increasing the $500,000 cap on non-concessional super contributions proposed in the May budget to $750,000 or changing the commencement date of the cap.

When asked to rule out the changes, a spokeswoman for the treasurer said the government was consulting on the “implementation” of the super reforms taken to the election.

“The government will consider technical changes to assist in the implementation of these necessary reforms,” she said.

On Thursday, Morrison addressed exemptions to the cap in an interview with Sky News. He said he had flagged an exemption for settlement of property sales before the election, and other exemptions for life events including divorce settlements were still “being worked through”.

Morrison said there was “speculation” that lottery wins and inheritances would also be exempt, but said they were “not things being contemplated by the government nor have they been”.

Earlier in August, Morrison indicated that insurance payouts as a result of accidents would also be exempt from the cap.

The impact on the budget of the life events exemptions, raising the cap or changing its commencement date were still unclear.

The shadow treasurer, Chris Bowen, seized on the report, saying it was “humiliating” for the treasurer to make the changes in an effort to calm the Liberal backbench.

“We shouldn’t have to read about Scott Morrison’s climbdown and back-flip on the back page of the Financial Review, leaked out by the government,” he said.

“[Morrison] should be on the front foot and tell people, the superannuants of Australia, those who have invested in good faith under existing rules, just what his policy is.”

Bowen said it appeared superannuation legislation would not be ready for some time “because the government is at war with itself” over the issue.

Since the election, the superannuation policy has come under fire from conservatives within the Coalition, including threats from MP George Christensen to cross the floor and warnings from senator Eric Abetz that the policy cost it support from its base.

Labor wants the proposed superannuation changes to be reviewed, particularly to determine whether they are retrospective because the lifetime cap on non-concessional contributions is back-dated to 2007.

Asked about the possible u-turn on 3AW radio in Melbourne on Friday, Malcolm Turnbull said “the treasurer is consulting with colleagues”.

“Our policy is the one we took to the election, the one that was set out in the budget, but he is ... carefully consulting with our colleagues, and of course other interested parties and stakeholders,” he said.

In July, Ian Yates, chief executive of the Council on the Ageing, said the Coalition has an obligation to voters who had returned it to government to deliver the changes which would make the super system more fair.

On Friday, senator John Williams told Guardian Australia he had received “very negative feedback from constituents” that the backdated life-time cap had “changed the goalposts half way through the game”.

Williams said when the Senate inquiry into financial advice restarts he would investigate complaints he had received about life insurance products offered through superannuation.



He cited the revelations of CommInsure’s failure to payout on claims, and the example of a man who had committed suicide and did not receive a life insurance payout, despite paying premiums, because his super balance was below a required threshold.