Police believe people as far away as the South Island may have been scammed when 100 Tongans turned up at Auckland Airport last week to collect airline tickets that never existed.

The group paid a fraudulent immigration adviser $250 each for return airfares from Auckland to Tonga.

Waikato police today said they had been contacted by 15 people who had bought the tickets but were aware of many more in Auckland and others as far away as Wellington and the South Island.

Police are working to establish the extent of the scam and want to hear from anyone who fell victim to it.

"Often the circumstances change but the basics remain the same, if something seems too good to be true then it probably is and we urge people to check the bona fides of anyone trying to sell items or services at heavily discounted rates,'' acting Detective Senior Sergeant Andy Bu Bear said.

"All too often it is the people who are the most vulnerable and who can least afford it that are targeted, if something doesn't appear right it probably isn't and in situations such as this we recommend people use the services of reputable travel agents, air lines or service providers." 

The airline scam was the latest in a long-running string of fraudulent activity targeting overstayers in the Tongan community. They included asking Tongans to pay up to tens of thousands dollars on the promise of gaining permission to stay in New Zealand.

Other scams had involved asking Tongans to hand over their passports and increasing amounts of cash to secure a residency visa.

Immigration New Zealand said the problem was the victims were too afraid to speak up for fear of being deported.

Tongan community advocate Amelia Schaaf said there was a disturbing trend of manipulations of Tongans by Tongans, even among licensed immigration advisers.

"They are cheating Tongan people with them charging $3000 to $5000 and no work being done."

She said people were afraid to speak up.

"What safeguards are there for them? They are overstaying and breaking the law but if they are being cheated there needs to be a system that protects them if they come forward."

Immigration New Zealand spokesman Dean Blakemore said it was concerning to hear of the scams and while his staff were "committed and passionate about helping people get favourable outcomes" he could not guarantee those who came forward would be allowed to stay in New Zealand.

"But without a compliant we can't have an investigation."

Ana Uvea came forward to make a statement after more than a year giving money, totalling $10,000, to Kolini Vaka.

Vaka said she could get her family, including her father who is dying of cancer, residency visas.

"They said we could get jobs and have a house and I believed her, she was so good and explaining it. She manipulated me and I failed."

Tongan journalist Ulualo Pouhila, who has been investigating the scams, said it had been going on for too long.

"The whole mess is far, far bigger than we thought. It's raw and it's embarrassing."

Waikato police want anyone with information on the identity of the airline scammers, or who bought tickets from them, to contact them on 07 858 6200 or anonymously on Crimestoppers 0800 555 111.

- © Fairfax NZ News