ONE of Australia's biggest raids by immigration officers has netted 90 illegal workers at Mooroopna.

Immigration officials and Australian Federal Police officers swooped on a caravan park at Mooroopna, west of Shepparton in Victoria's north, and detained 85 workers and five students.

A Department of Immigration spokesman said the 61 men and 24 women, mostly from Malaysia and Indonesia, were found to be either unlawful non-citizens or working in the local horticulture industry in breach of their visa conditions.

After being taken to detention centres at Maribyrnong and Villawood, they would be deported, he said.

Five overseas students who had worked in breach of their visa conditions were served warning notices.

The spokesman said investigations were continuing into the circumstances of their employment, including any involvement by labour hire organisers.