The Coalition’s “big stick” energy legislation to break up power companies is a “backdoor to privatisation” of electricity assets in states that have kept them in public hands, Mark Butler has warned.

On Sunday Labor’s shadow climate change spokesman gave a clear signal it will continue to oppose the legislation in an interview renewing his calls for an “unsparing” election review and refusing to recommit to a 45% emissions reduction target by 2030.

On Saturday the Australian Financial Review reported the Morrison government is set to reintroduce legislation to give the treasurer power to compel companies to supply electricity on certain terms and for courts to force energy companies engaging in anti-competitive conduct to sell off assets.

The bill was shelved before the election due to lack of Senate support and the risk of amendments hostile to coal, but Labor’s leader Anthony Albanese has so far refused to state a position on the bill after the surprise May election defeat.

Butler told ABC’s Insiders that Labor would look to see if any changes had been made to the legislation but noted that the Australian Competition and Consumer Commission had “explicitly rejected” the idea, suggesting it is not in consumers’ interests.

“The Energy Users Association representing the biggest users of electricity in this country also said they were concerned this bill would simply smash investor confidence and force power prices up,” he said.

“There’s also the added concern that we pointed to that this appears to be a backdoor to privatising electricity assets in Queensland and [Western Australia] and Tasmania where their communities have time and time again rejected the idea that their publicly owned assets should be put in private hands.

“We have some very serious concerns about this.”

Butler responded to a report that Labor may have to ditch its interim target of 45% emissions reduction by 2030 by noting that “all our policies are up for review” since the election defeat.

Butler said setting medium-term targets is still best practice but noted the 45% target was set in 2015, suggesting he could not put a precise number or year on a new target.

“What our position will be at 2022 at the election, obviously I’m not in a position to announce four months out from the last election.”

He said Labor wanted to keep global warming below 1.5C and is committed to “net zero emissions by the middle of the century and medium-term targets consistent with those principles informed by the best scientific and economic advice”.

Butler criticised the Coalition for the drought minister David Littleproud denying knowledge of a link between climate change and bushfires – a position he later retracted – and Australia’s record of steadily rising emissions.

He said Scott Morrison would not attend the UN climate summit because Australia’s 26% emissions reduction target is “unanimously regarded as grossly inadequate, [and is] consistent instead with more like 3C or 3.5C of global warming which would be utterly catastrophic”. Australia is set to miss the “inadequate” 2030 target “by a mile”, Butler said.

Asked about ALP president Wayne Swan’s view that Labor should stick to its tax-and-spend agenda to fix inequality, Butler replied that Swan was “very experienced” and entitled to put the view but even he “accepts … that this was a very deep election loss”.

Butler said Labor needed “some deep reflection and that includes over our taxation policies, the spending commitments they were intended to fund, climate and energy and every other policy area” because it lost its third election in a row, with the lowest primary vote in 100 years to an outfit “Morrison himself described as the Muppet Show”.

Butler also rejected allegations of racism in Labor questioning the government about Liberal MP Gladys Liu’s links to Chinese-government associations, noting it is pursuing the same questions as the national media.

He attacked the Coalition’s record, including former attorney general George Brandis’s declaration people have “the right to be a bigot” in the context of attempting to water down race hate speech laws, and Morrison’s decision to label Sam Dastyari “Shanghai Sam” when he was embroiled in a donations scandal.