SYDNEY (AFP) - Australia on Friday denied fresh claims of asylum-seeker abuse by its navy as "completely unsubstantiated" while confirming for the first time that it was turning boats back to Indonesia.

Immigration Minister Scott Morrison broke with months of secrecy over the government's military-led Operation Sovereign Borders people-smuggling crackdown to concede that boats were being turned around.

"What I have confirmed today is... that any vessel that seeks to illegally enter Australian waters will be intercepted and will be removed from our waters and our contiguous zone," he said. The minister would not confirm how many boats had been turned back but said "none shall pass is our objective".

No people-smuggling boats have arrived in Australia since December 19 - the first time in six years that January has passed without a single boat arrival.

Mr Morrison would not comment on whether confirmation of the policy, which has angered Jakarta, would increase tensions with Australia's strategic neighbour.

"All I have simply said today is that Australia will respect our neighbour's sovereignty, we will respect our sovereignty and that involves any vessel seeking to illegally enter Australia being intercepted and removed from our waters," he said "Now, that is about what is happening on our side and on our border and that is about our sovereignty, and I know for a fact that Indonesia respects Australia's sovereignty as we do theirs."

Relations with Jakarta have been strained since a phone-tapping row late last year, with recent revelations that the navy strayed into Indonesian waters during asylum-seeker operations further testing ties.

Mr Morrison's remarks came as fresh claims emerged from asylum-seekers turned back to Indonesia by Australia's navy of mistreatment suffered during the military turn-back.

Somali asylum-seeker Boby Nooris told the Australian Broadcasting Corporation he was sprayed in the eyes by officers with a substance that made them sting and he stumbled onto a hot engine pipe, burning his hand.

"I felt pain like chillies went into my eyes. I could not see anything, it was dark, and I threw myself into the sea," Mr Nooris said.

Mr Morrison said navy personnel carried "personal defensive devices" but denied any suggestion of mistreatment.

"They are used in accordance with their training and in accordance with strict guidelines, and any suggestion of mistreatment or misuse of force or misuse of any of these devices that are available to them is completely unsubstantiated, completely without basis and is rejected by the government," he said.

"We are not running a welcoming service out there. We are not running some sort of welcoming committee," added Mr Morrison.

"What we are doing is implementing a policy which is strong, which can be tough." Mr Morrison is due to appear before a parliamentary inquiry into border protection policy Friday where he said he would be "standing by the people who are running our operations".

Hundreds of asylum-seekers have died making the dangerous sea voyage from Indonesia to Australia in recent years, prompting the so-called Sovereign Borders crackdown.