Bill Shorten has left the way open for Labor to endorse asylum seeker boat turnbacks, as a former senior Indonesian official slammed the policy.
Labor's national conference to be held in Melbourne next month will debate changes to the party's asylum seeker policy.
Sections of the party want an end to mandatory detention and offshore processing, while others want to match the federal government's "border protection" strategy, including boat turnbacks.
The national Left faction will meet in Sydney this week to consider its position.
Mr Shorten, a key figure in the party's Right faction, late last year said no case had been made for changing Labor's opposition to boat turnbacks.
But after Right faction members such as Joel Fitzgibbon went public with their support for the policy, Mr Shorten's language has softened.
"Part of the dilemma with the turnback policy is the government insists in shrouding it in secrecy," he told reporters in Melbourne on Monday.
"We want to see what the policies are and how they are working."
There are concerns within Labor that boat turnbacks are damaging Australia's relationship with Indonesia.
Former Indonesian foreign minister Marty Natalegawa, who was in Canberra on Monday for a leadership conference, said turnbacks were "inherently incompatible" with good bilateral relations.
"National efforts should not be seen at the expense of bilateral and regional co-operation," he said.
Former Australian ambassador to Indonesia Bill Farmer told the same conference: "I do believe we go too readily for the dog whistle on boats."
Mr Shorten said Labor's policy would be compassionate but he was determined to "make sure that never again do the seaways between Java and Christmas Island become the opportunity for people smugglers to put unsuspecting people into unsafe boats and drown at sea".
Labor for Refugees convenor Robin Rothfield says turnbacks needlessly put asylum seekers and boat crews in danger.
"What it stands to lose is it makes itself out to be a cruel, opportunistic, shameless party which has completely forgotten the values of the party," he said.
Immigration Minister Peter Dutton said taking turnbacks off the table and allowing the smugglers to restart would be "unconscionable".
"It's why Bill Shorten has to come out and talk quickly as to what his position is," he said.
The minister predicted Labor's national conference would agree to turnbacks but also to boost numbers of refugee places.
However, if elected the policy would unscramble and the boats would start again under Labor.
Prime Minister Tony Abbott, visiting Singapore for talks on trade and security, said he did not see his trip as being driven by problems with other Asian neighbours such as Indonesia.
"I don't take a zero sum view of the world ... if you strengthen one friendship, you make it easier to strengthen other friendships, you make yourself a better and more appealing friend."
