The Chief of Navy, Vice-Admiral Ray Griggs, has flatly denied that Australian sailors inflicted burns to asylum seekers' hands by forcing them to hold hot sections of a boat engine.
After footage and photos emerged showing male asylum seekers with burn-like injuries to their hands, Admiral Griggs took to Twitter on Wednesday afternoon to dismiss the claims as baseless.
''Based on everything I know there is no basis to these allegations - none,'' he wrote.
Challenged further by other Twitter users to deny them outright, Admiral Griggs replied: ''I just did!!!!''
Prime Minister Tony Abbott also spoke out in support of the navy when addressing reporters in Davos, Switzerland.
He said there was "absolutely no evidence" to support the claims made by the asylum seekers.
"Who do you believe?" Mr Abbott asked. "Do you believe Australian naval personnel or do you believe people who are attempting to break Australian law?"
"I trust Australia's naval personnel."
Mr Abbott said the asylum seekers "should be able to produce some evidence and there's no evidence whatsoever to back them up".
Indonesian police are investigating the incident.
Foreign Minister Julie Bishop says Australia will co-operate with the inquiry.
''I cannot imagine for a moment that the professional people that we have in our forces would have behaved in that fashion,'' she told reporters in Washington overnight.
''But of course if there is any co-operation we can extend to ensure that these allegations are scotched then we'd be prepared to do it.''
Acting Chief of the Defence Force, Air Marshal Mark Binskin, joined the rebuttal of the claims, saying he had ''every confidence in the dedication of our people and their ethical approach to the conduct of operations in difficult and often dangerous conditions''.
One source told Fairfax Media the asylum seekers were believed to have suffered the injuries while trying to sabotage the boat's engine before they were intercepted by the navy.
Earlier in the day, Immigration Minister Scott Morrison stood firm in his refusal to hold an inquiry into the claims, which he blasted as ''sledging'' of navy personnel.
Mr Morrison said no inquiry was needed because the claims were unsubstantiated and the asylum seekers and people-smugglers had strong motivations to lie. ''I've been given assurances about [the navy's] conduct and I believe those assurances because I believe in those individuals,'' he said.
Photographs obtained by Fairfax Media show at least one man with burns on his hands. Bashka Ibrahim Nooris and Ahmed Ali Noor, from Somalia, said they had been made to put their hands on the boat's muffler.
Rote police chief Hidayat said: ''We did see burn injuries on their palm. It seems they were told to hold part of the boat engines; it was hot,'' he said.
The allegations relate to a boat that sailed from Kupang, in West Timor, bound for Darwin in late December.
The ABC on Wednesday aired footage of two male asylum seekers being examined by Indonesian officials for injuries to their hands.
Mr Morrison said there had been no police investigation in Indonesia. However, the ABC quoted Kupang Chief detective Sam Kawengian saying the claims warranted investigation and that he had invited Australian authorities to travel to Kupang to view evidence.
Professor Stephen Shumack, president of the Australasian College of Dermatologists, said the injuries could be burns from hot metal, though he stressed it was impossible to diagnose for certain from the images.
He said the injuries could also be friction burns or some other external trauma, but ruled out lesions caused by a skin disease. He said they appeared ''reasonably fresh'', estimating the injuries were five to 10 days old at the time the pictures were taken, which falls within the correct time frame for the asylum seekers' claims.
Meanwhile, the government announced that an urgent inquiry into how navy and customs ships breached Indonesian territorial waters would report back by February 10 - though the two senior reviewers could be granted extra time if they need it. But there is no guarantee the report into the incidents will be publicly released.