Australian Immigration Minister Scott Morrison said Monday there was "no rhyme or reason" as to why Indonesia had accepted two boatloads of asylum-seekers picked up by Australian vessels but refused others.
Thousands of asylum-seekers, many from Iran and Afghanistan, board rickety, wooden boats in Indonesia every year to try and make the perilous sea crossing to Australia.
Stopping the influx was a key issue at September elections won by Tony Abbott, who vowed to turn boats back to Indonesia when safe to do so -- a policy received coolly by Jakarta.
Morrison said two boatloads of asylum-seekers picked up by Australian ships had previously been accepted by Indonesian authorities.
But Jakarta refused to take about 60 people picked up south of Java by an Australian vessel on Thursday, and on Saturday Morrison decided to transfer them to Australia's remote territory of Christmas Island for processing in Papua New Guinea or Nauru.
"There's no real rhyme or reason to it necessarily," Morrison told commercial radio when asked why some boats were accepted and others rejected.
"I think this last instance became very problematic because it went very public," he said, adding that he had promised Jakarta that such incidents would be handled in a direct and discreet manner.
In the latest incident, Morrison decided to take the group to Christmas Island for processing rather than risk keeping them and the crew of the Australian boat at sea after a three-day impasse.
He said there had been no prospect of turning back the latest boat, which was intercepted in Indonesia's search and rescue zone and close to its coastline, because it was sinking and had been deemed unseaworthy. The vessel was later scuttled at sea.
Morrison denied that the government's border protection policy was failing but admitted that the situation was "very frustrating".
The minister said the number of unauthorised boat arrivals had dropped significantly since the government was elected, with none for almost three weeks before latest incident.