Greens demand answers on boat 'pay-offs'

There's a big question as to whether paying people smugglers to return boats constitutes a crime, the Australian Greens say.

Questionable expense claims from treasurer Joe Hockey and senator Sarah Hanson-Young have emerged. (AAP) Source: AAP

The Australian Greens are demanding the prime minister be straight with the public and confirm if Customs officials have been handing out cash to turn back asylum seeker boats.

Immigration spokeswoman Sarah Hanson-Young says it's laughable Tony Abbott is arguing details are being withheld on operational grounds.

"Either this happened or it didn't," she told reporters in Adelaide on Friday, adding there were questions about whether a crime had been committed.