A donation to the Australian Workers Union has come under scrutiny as it did not appear in electoral disclosures.
A donation of $47,500 was made to the Victorian branch of the AWU and attributed to mining company Roche, a subsidiary of Downer EDI, in 2007 in the lead up to the successful Rudd/Labor election campaign.
The AWU told the ABC the amount was paid voluntarily by union members employed by Roche Mining towards legal costs associated with an industrial dispute.
In 2006 the AWU and four of its officials were fined $56,000 over an illegal meeting which led to a strike at a site operated by Roche Mining in Western Victoria.
The Royal Commission into trade union governance and corruption has scrutinised records from the AWU, uncovering apparent inconsistencies in account keeping, including discrepancies which show increases in union income for years in which membership declined.
Federal opposition leader Bill Shorten will give evidence to the Royal Commission on July 8 to answer for his involvement as national secretary of the AWU.