Signs of a growing split between Australia and the United States over an unproven theory that the coronavirus came from a Wuhan laboratory have emerged, amid claims the US embassy may have leaked a dossier linked to the allegations.

The Sydney Morning Herald on Thursday reported that Canberra was increasingly concerned the Trump administration’s promotion of claims that the novel coronavirus began in a lab could undermine its push for an independent inquiry into the origins of the pandemic and a ban on the sale of exotic live animals.

“The Americans pushing the lab theory kind of discredits that initiative,” said Richard McGregor, a senior fellow at the Sydney-based Lowy Institute. “It prejudges it, which in a way contaminates the idea that any inquiry supported by the US can be independent.”

The SMH report, which cited multiple unnamed officials, said there were “widespread suspicions” within the Australian government that a dossier, revealed in an earlier article by a rival newspaper group, had been leaked by the US embassy to help push a “narrative in the Australian media that could be counter to the beliefs and interests of its hosts”.

The dossier appeared to match the description of a research report that was based on public information, including news reports, according to the SMH, but “contained no information that was generated from intelligence gathering”.

The US embassy in Canberra did not respond to a request for comment from the South China Morning Post.

Bob Carr, a former Australian foreign minister, said the US embassy could have denied the reports of the leak if they were untrue and suggested such a “brazen intervention” would be widely seen as political interference if carried out by China.

“That said, it continues to be my view that China should demonstrate to the world that it has closed – city by city, county by county – the trade in wild animal meat and enforce the ban ruthlessly,” Carr said.

On Monday, the rival Daily Telegraph reported that Western governments had compiled a “15-page research document” accusing China of destroying evidence of the initial coronavirus outbreak as part of an “assault on international transparency”.

The newspaper said the “Five Eyes” intelligence partners of the US, Australia, Britain, Canada and New Zealand were investigating the possibility the virus had accidentally leaked from the Wuhan Institute of Virology, where scientists – including researchers trained and funded by the Australian government – had genetically modified coronaviruses that are transmittable from bats to humans.

When contacted, Sharri Markson, the author of the Daily Telegraph report, did not confirm or deny whether the dossier was based on open-source information, but said “at least” two Western governments had contributed to the document and accused the SMH of mischaracterising its contents as being primarily about the origins of the virus instead of “China’s cover-up”.

Markson said the SMH had “not criticised Chinese authorities’ response to [the] coronavirus like we have”.

The controversy follows diverging public statements about the origins of the virus from the governments of the two close allies in recent days.

Australian Prime Minister Scott Morrison, whose push for an international inquiry into the cause of the pandemic has strained relations with Beijing, said on Tuesday it was “most likely” the virus had emerged in a wildlife market, reiterating previous remarks about the pandemic probably having natural origins.

The Australian leader’s comments came after US Secretary of State Mike Pompeo said on Monday there was “enormous evidence” the virus had originated in a lab, and after President Donald Trump last week claimed he had seen evidence to support the as-yet unsubstantiated theory.

On Thursday, Pompeo said the intelligence community was still “figuring out precisely where this virus began”, while denying any inconsistency with his earlier statements.

The US Office of the Director of National Intelligence said in a statement last week it agreed with “the wide scientific consensus” that the virus was not man-made or genetically modified and was examining “emerging information and intelligence to determine whether the outbreak began through contact with infected animals or if it was the result of an accident at a laboratory in Wuhan”.

Beijing has blasted the lab theory as groundless and challenged the US to produce evidence for the claim.

Hugh White, a professor at the Strategic and Defence Studies Centre at Australian National University, said that while Canberra had often taken a softer line on Beijing than Washington – such as declining to follow its lead in deeming China a “strategic rival” – its efforts to disassociate itself from the lab theory were noteworthy.

“This is especially notable because Canberra just last week seemed willing and even eager to echo Washington’s broader efforts to pin the blame for the pandemic on China, when it launched its proposal for an independent inquiry in terms that clearly suggested they believed Beijing was to blame,” said White.

“One explanation is that Canberra’s eagerness to distance itself from the Wuhan lab theory is an attempt to placate Beijing after Beijing’s angry reaction to last week’s initiative. But it may also be that Canberra is just in a muddle, with different voices giving out different messages,” he said.

However, Yun Jiang, a former Australian government policymaker who serves as director of the China Policy Centre, said Canberra was unlikely to pursue any grievances with Washington despite its apparent attempt “to influence public opinion in Australia”.

“The alliance with the US is extremely important to Australia, especially to the current government,” Jiang said. “Despite some differences with the Trump administration, we have seen that so far the Australian government has not criticised the US government publicly – and it is unlikely to do so now.”