The stood aside Health Services Union boss, Michael Williamson has been arrested. He allegedly attempted to hinder police in their investigations into fraud within the HSU.

The sixty year old Williamson was arrested when he arrived at Sydney's Maroubra Police Station this morning. He will be charged later today over an alleged HSU fraud involving up to $20 million.

The investigations have been conducted by the Fraud & Cybercrime Squad under Strike Force Carnarvon which was established in September last year.

Detectives say they intend charging him with a number of offences relating to hindering police in their investigations.

Whistleblower Kathy Jackson has claimed massive fraud has been prevalent for years with the union.

Gillard Minister, Bill Shorten, attempted to have the investigation into the HSU shut down by sequestrating the union.

Minister Shorten has also allegedly recommended the AWU not pursue its stolen funds defrauded by Bruce Wilson because it necessarily involves Julia Gillard.