Paying people smugglers to turn a boat around is akin to paying murderers not to kill or paying drug dealers not to make ice, Labor's immigration spokesman Richard Marles has said.

Mr Marles also defended revelations that people smugglers were paid under the former Labor government, saying it was vastly different for intelligence agencies or police to pay "informers" to infiltrate or undermine a criminal syndicate, than to push boats back to Indonesia.

"That is very different to paying the criminal syndicate to undertake a certain action," Mr Marles said during a press conference in Canberra.

"The allegation that we had last week is the equivalent of paying drug dealers not to make ice, it is the equivalent of paying murderers not to go out and murder. It's paying people smugglers to do reverse people smuggling. It is a very different proposition indeed," he said.

Asylum seekers and the Indonesian police chief claim that an Australian official by the name of "Agus" boarded a boat carrying 65 asylum seekers and gave each crew member $US5000, on the condition that they return to Indonesia and the captain never people smuggle again.

Fairfax Media has since revealed that cash payments had also been made to members of Indonesian people-smuggling rings by Australian intelligence officials for at least the past four years, including under the former Labor government.

Immigration Minister Peter Dutton has refused to comment on whether there was a difference between paying people smugglers to perform an act, than to gain information.

"Suffice to say I'm not making comments in relation to hypothetical matters around national security," he said on Thursday.

"What we've been able to do in Operation Sovereign Borders is to, within the law and within our international obligation, stop the boats. And we will make sure that we do whatever we can within the law and within our international obligations to keep these people smugglers out of business."

Mr Marles said Labor would continue to put pressure on the Abbott government to reveal whether Australian authorities paid people smugglers to turn a boat around.

"There are real questions for the government to answer and they've not answered them," he said.

On Thursday the party will also decide if it will support a Greens' led inquiry into the allegations that the crew of people smugglers were paid $US5000 each.

"The idea that people smugglers have half a chance when they come up next to an Australian Navy vessel of getting a wad of Australian taxpayer funded cash is a real problem, it should be a real concern to every Australian."

However, it is understood that Labor is considering its position on whether it will endorse turning boats back as part of its immigration policy. Turn backs is one of few differences between Labor and the Abbott government's stance on asylum seekers.