Adam Gartrell – Five Australians trapped in Indonesia's Papua province for more than nine months expect to fly home on Wednesday after authorities thwarted their plans to leave on Tuesday.

The middle-aged Queenslanders – pilot William Scott-Bloxam, his wife Vera, and passengers Keith Mortimer, Hubert Hofer and Karen Burke – had planned to fly out of the Papuan town of Merauke on Tuesday afternoon after Indonesia's immigration department issued a document finally lifting an order that had blocked their departure.

But prosecutors in Merauke withheld final permission for them to leave, apparently dissatisfied at receiving an electronic version of the document, not the original.

By the time prosecutors finally agreed to let them go it was starting to get dark, so the group opted to fly out on Wednesday morning.

The group's lawyer, Mohammad Rifan, slammed the prosecutors for their "arrogance". "We are very disappointed with their attitude," he said. "They just don't want to set the Australians free. They didn't deserve to be treated like this."

Ms Scott-Bloxam, said the group was trying not to be angry about Tuesday's showdown. "We have to be like that, otherwise I'd slap someone, and I don't want to do that," she said.

Arrested last September for flying their light aircraft into the troubled province without visas or proper clearance, the five were sentenced to harsh prison terms earlier this year.

But their convictions were dismissed by Indonesia's Supreme Court on June 10, and they were ordered to return to Australia once Indonesia's byzantine bureaucracy had finalised paperwork.

Papua has been troubled by a low-level separatist insurgency since the 1960s. Journalists are barred from entering Papua without special permission, and human rights groups have accused the Indonesian military of human rights abuses there.