Kevin Rudd is expected to announce details of the pilot scheme later this month, which would bring Pacific Islanders to Australia for fruit-picking and other seasonal work.

The National Farmers Federation strongly supports the scheme, which would fill critical labour shortages in agriculture and horticulture.

But unions, such as the Construction Forestry Mining and Energy Union, believe it will lead to the exploitation of foreign workers or "Mexicanisation" of Australia's job market and lower wages and conditions for all workers.

"There's been absolutely zero detail (on the scheme)," shadow minister for foreign affairs Andrew Robb told ABC radio yesterday.

"Does Australia want unskilled labour coming in from a number of Pacific Islands, given there are half-a-million unemployed people in our country already?"

Mr Robb called for debate on the merits of the scheme, which is expected to be announced by the Prime Minister at the Pacific Islands Forum in Niue.

Foreign Minister Stephen Smith said the proposed trial scheme would support development in the Pacific, where many families rely on remittances.

If Australia decides to pursue it, it would be "demand driven and start with a limited number of countries participating on a trial basis", he said.

MPs such as the Nationals' Kay Hull in the Riverina support the scheme, while others such as former immigration minister Kevin Andrews have doubts.

Under the trial program, up to 5000 workers could come to Australia for between six and 12 months.

They are likely to be restricted to the horticultural industry in the trial phase.

Parliamentary Secretary for Pacific Island Affairs Duncan Kerr said any scheme would have legislative safeguards to prevent exploitation.

If Australia introduces the scheme, regulations will ensure workers are paid award wages, housed appropriately, and have access to the same protection as Australians have.

"We would certainly be building in mechanisms to deal with some of the practical concerns that people have raised," Mr Kerr said.