Sydney -

Australian Prime Minister Tony Abbott defended the government's secrecy over its border protection policy on Thursday after reports that boats had been turned back to Indonesia and asylum-seekers mistreated.

Under the conservative government's hardline Operation Sovereign Borders, officials refuse to discuss “operational matters”.

This has meant reports that at least one boat was forcibly turned or towed back to Indonesia, and that members of the Australian navy subjected those on board to verbal and physical mistreatment, have not been addressed.

The government has also refused to confirm or deny that it is planning to buy 16 hard-hulled lifeboats to ferry asylum-seekers to Indonesia, sparking claims from the Labor opposition that it is overseeing a “Stalinist”-style media blackout.

Abbott said he would rather have the boats stop arriving in Australian waters than provide a running commentary as “sport for public discussion”.

“I'd rather be criticised for being a bit of a closed book on this issue and actually stop the boats,” he told Sydney commercial radio.

“The point is not to provide sport for public discussion. The point is to stop the boats.

“I'm pleased to say it is now several weeks since we've had a boat, and the less we talk about operational details on the water, the better when it comes to stopping the boats.”

His comments follow claims by an asylum-seeker to AFP on Wednesday suggesting people on a boat towed back to Indonesia, which is the major transit point for would-be refugees to Australia, had been mistreated by the Australian navy.

Yousif Ibrahim from Sudan claimed they were handcuffed and called insulting names. He said one person was beaten with shoes after their vessel was intercepted and towed for four days back towards Indonesia, arriving at Rote Island on Monday.

“We asked for water, they didn't want to give us. They called us inhuman words, like illegal refugees, monkeys from Africa,” he told AFP, adding that two sick children were denied medicine.

While refusing to comment on the claims, Australian Immigration Minister Scott Morrison on Wednesday insisted that Australian personnel act with the “highest levels of professionalism”.

Australia's tough policies aimed at stemming the flow of asylum boats - a key plank of Abbott's successful 2013 election campaign - have irked Jakarta, which has warned that turning boats back could breach Indonesian territorial sovereignty.

Tensions between the neighbours have been strained for months after a diplomatic row erupted in November over claims Canberra tried to tap the phones of Indonesian President Susilo Bambang Yudhoyono, his wife and ministers.

Abbott on Thursday described Australia's relationship with Indonesia as “strong” and marked by “a lot of cooperation and mutual understanding”.

He said he understood Indonesia's concern for its sovereignty “but when these boats keep coming illegally to our country, that is a sovereignty issue for us”.

“It's absolutely non-negotiable - these boats will stop, these boats must stop, and we will do whatever is necessary, consistent with our international obligations and ordinary decency, to stop the boats,” he said. - Sapa-AFP