The ABC revealed yesterday that visas for asylum seekers would be charged under a new category, Australian regional processing visas, which will cost $3000 a quarter for each asylum seeker.

If the camp reaches its 1500-person capacity, the scheme would cost $90 million over five years.

A spokesman for Immigration Minister Chris Bowen said it was ''reasonable'' that people transferred to Nauru held valid visas.

''No costs have been paid at this stage,'' he said. ''The visa charges are the subject of discussions between Australia and Nauru, so it would not be appropriate to comment further. These ongoing costs are factored into the operating budget for Nauru.''

But a spokesman for the Nauru government said the matter had already been resolved.

''This was agreed to, or it was all part of the original negotiations,'' he said, adding that the measures had already passed through the Nauru parliament.

But the opposition and Greens said taxpayers would bear the brunt of Labor's scheme.

Meanwhile, refugee advocates in Australia said yesterday that most of the 381 asylum seekers on Nauru were on a one-day hunger strike, with protesters calling on the government to close the camp and begin processing their claims immediately.

The Department of Immigration rejects the claim that most asylum seekers on the island are taking part in a hunger strike. It considers people to have gone on hunger strike if they are observed to be missing three consecutive meals.

But Refugee Action Coalition spokesman Ian Rintoul said he had spoken with three asylum seekers via Skype, all of whom said the hunger strike had begun yesterday and would continue to this morning.