Labor leader Bill Shorten insists his party is united on asylum-seeker policy despite an ALP candidate criticising boat turnbacks.
Immigration Minister Peter Dutton used the return of three boatloads of asylum seekers since the start of the year to argue on Monday that the government is more committed than Labor to stopping people-smuggling.
The latest was a group of 12 men, women and children from Sri Lanka who arrived near the Cocos (Keeling) Islands last week and returned on May 6.
"They were in a good state - they had made the journey down and they quickly made the journey back," Mr Dutton told reporters in Brisbane.
The returns showed asylum seekers could not seek the help of criminal people smugglers and expect to get to Australia, he said.
The minister seized on a comment by Sophie Ismail, Labor candidate in the seat of Melbourne, who told Fairfax Media: "I have concerns about turnbacks. I don't think they should be on the table."
"Labor is divided when it comes to border protection," Mr Dutton said.
Mr Shorten said his party's asylum-seeker policy was clear.
"We will not put the people smugglers back into business, we will not allow policy which sees the mass drowning of vulnerable people seeking to come to this country," he told reporters in Cairns.
He acknowledged the issue had been a difficult one for the ALP's national conference but the party had settled on support for turnbacks and offshore processing.
"When it comes to people smugglers and turnbacks and not having onshore processing by people who are smuggled here by criminal syndicates, we are not for turning on our policy," he said.
Labor frontbencher Anthony Albanese said he would not condemn candidates for putting forward views on boat turnbacks.
"They are entitled to do so," he told reporters in Sydney.
Mr Albanese, a Left faction heavyweight, argued against turnbacks at the conference but stands by the party's position.
Meanwhile, Mr Dutton said talks with Papua New Guinea to resolve the Manus Island situation would stretch beyond the election.
The immigration centre's future was cast into doubt by a PNG Supreme Court ruling it was illegal.
"We will have what I think will be detailed and long-run discussions with PNG to help them in relation to this particular issue," Mr Dutton said.