Amnesty International has condemned the government’s “secretive” border operations.

The Amnesty International report, released on Thursday, claimed Operation Sovereign Borders was a “lawless venture” and called on a royal commission into its affairs.

It also claimed Australian officials in May paid $US32,000 to six crew who were taking 65 asylum seekers to New Zealand, to get them to return to Indonesia instead.

A second incident allegedly saw crew paid after a boat was turned back to Indonesia in July.

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The report claimed the 15 passengers and two ship crew on board the smuggling boat were separated for a week before being turned back.

“By this time the boat crew had two new bags that the passengers had not seen before,” the report alleged.

“When the passengers became suspicious and threatened to open the bags the Australians repeatedly told them not to.”

Immigration Minister Peter Dutton maintained the operations were legal.

“People on intercepted vessels are held lawfully in secure, safe, humane, and appropriate conditions by the personnel of the Australian Border Force and the Australian Defence Force,” a spokesperson for Mr Dutton said.

“To suggest otherwise, as Amnesty has done, is to cast a slur on the men and women of the Australian Border Force and Australian Defence Force.”

But report author Anna Shea labelled the actions of the ABF and ADF as transnational crime.

“Australia appears willing to do absolutely anything to stop people seeking asylum from reaching its shores,” she said.

“The idea that the ends justify the means is extremely concerning.

“When governments say that ‘on water matters’ are exempt from public scrutiny, in effect they are saying that they can do anything they like.

“This is a very dangerous and profoundly undemocratic idea, and must not be replicated in Europe or elsewhere.”

The report came a day after former Prime Minister Tony Abbott told a charity event in London that Europe should toughen its policy and tighten its borders against refugees to shield from the “witches’ brew of danger and complexity” in the Middle East.

-with AAP