Sydney Greek-Australian George Alex is accused of giving cash to a union official.

One of Australia’s most colourful businessmen, “Big Jim” Byrnes, told ABC this week, he witnessed one of the key targets of the trade union royal commission, George Alex, pass an envelope full of cash to a construction union official.

If true, Mr Byrnes’s statement would be the first eye witness account of unexplained money being paid to union officials, a key area being investigated by the commission.

Mr Alex is at the centre of a web of unsavoury characters, including outlaw bikers, violent standover men and convicted terrorists.

The son of Greek migrants, George Alex likes to portray himself as a man of charity, giving jobs or forming alliances with those who have fallen on hard times.

Over the years, Alex’s business partners have included convicted criminals, such as killer and since-murdered Hells Angels enforcer Steve Mitrovic and the Hells Angels drug trafficker Peter Sidirourgos.

His chief business partner, career criminal Joe Antoun, was shot dead last December.

Mr Byrnes is no innocent himself.

He was jailed for the supply of heroin in the 1980s and in the 1990s was the financial adviser to bankrupt businessman Alan Bond.