Merauke – Five Australians were sentenced Thursday to two to three years' jail for illegally landing a light plane in Indonesia's sensitive Papua province, thinking they could get visas on arrival.

Pilot William Scott-Bloxam was given three years while his four passengers received two years and were fined IDR25 million ($2,237) each.

The Australians looked shocked as the verdicts were read out. "I can't believe this," Vera Scott-Bloxam told the court before walking out with her husband, pilot Scott, trying to console her.

A lawyer for the Australians – the Scott-Bloxams, Hubert Hufer, Karen Burke and Keith Ronald Mortimer – described the sentences as harsh and immediately promised to appeal.

The two women and three men were arrested when they made an unannounced landing at Mopah airport in Papua's Merauke district on Sept. 12 after a flight from Horn island, off the northern tip of Australia's Queensland state.

They told police they were on a private sightseeing trip and believed they could obtain visas on arrival, although they weren't even carrying travel documents. They were detained on immigration offenses and held in an immigration detention facility in Merauke.

"The pilot William Scott-Bloxam has been proven legally and convincingly guilty of violating Indonesian transportation law by illegally entering Indonesian territory," Judge Des Benner Sinaga told Merauke district court.

He was fined IDR50 million and the aircraft was seized by the Indonesian government. "The four passengers have been found guilty of immigration offenses and must be jailed two years and each fined IDR25 million," the judge said.

Indonesia imposes tight restrictions on travel to Papua, where a small guerrilla force has been waging a low-level separatist insurgency since the 1960s and the Indonesian military is often accused of rights abuses. Journalists without special permits are barred from the region.

Australians are entitled to visas on arrival in other parts of Indonesia as long as they have valid passports and authorities find no reason to deny them.

Defense lawyer Efrem Fangoihoy said he was surprised at the length of the jail sentences. "I declare here firmly that we will file an appeal against the verdict, which we consider to be too heavy," he said.

Indonesian and Australian officials have said that while their actions were foolish, the five Australians posed no threat to Indonesia.

Defense minister Juwono Sudarsono told reporters after a meeting with his Australian counterpart Joel Fitzgibbon in September that the Australians were "looking for an opportunity to open up tourism."

Fitzgibbon said they had shown "very, very poor judgment" but added: "There isn't any evidence that they were up to what we would describe as any sort of activities that should be a threat to Indonesia."

Indonesia's foreign ministry said Thursday it couldn't comment on the verdict, but encouraged the Australians to appeal if they felt the sentences were unjust.