Union heavyweights targeted dissenters with intimidation and abuse, the royal commission into union corruption has heard.

Three years ago, union heavyweight Michael Williamson was cocky enough to stride onto stage at a national convention to the theme from Rocky, and during a private chat promised to destroy a whistleblower.

But today it’s the former Health Services Union (HSU) boss who is behind bars.

Ex-HSU official Marco Bolano on Monday detailed to the royal commission into union corruption the financial, legal and physical harassment dished out by senior union members and their underlings to whistleblowers.

“Enjoy the rest of your time in the union movement, I’m going to f***ing destroy you,” Mr Bolano said Mr Williamson told him at a HSU national convention in November 2011.

“What did you say? What? You’re going to destroy me from a prison cell,” Mr Bolano replied, predicting his then-boss’s fall.

Mr Bolano and fellow whistleblower Kathy Jackson had been on the outer with the union’s powerful NSW bloc after Ms Jackson reported Mr Williamson to police in September 2011, concerned he was fiddling the books and swindling cash.

Williamson, who was general secretary of the HSU from 1995 until 2012, was in March this year sentenced to at least five years in jail for “leeching” nearly $1 million from the union and then recruiting others to hinder a police investigation.

The abuse, according to Mr Bolano, started about a week after Ms Jackson alerted the NSW fraud squad to Williamson.

The pair were called “dogs” and “rats” during HSU teleconferences by Mr Williamson’s supporters and silenced whenever they tried to speak at meetings.

“You pricks. It’s all trumped up. We know you want to take over,” was a “constant retort of Mr Williamson’s supporters,” Mr Bolano said.

And two months later during the annual conference, Mr Bolano says they were followed and intimidated by NSW delegates under Williamson’s direction.

“Pity your plane didn’t crash on the way up … you f***ing Mexican c***,” one said to Mr Bolano, he told the commission.

Earlier on Monday, the commission heard federal MP David Feeney secured donations from a tobacco company to fund a candidate in HSU elections.

Mr Feeney denied the claims.

“I have not solicited a donation from Philip Morris for any purpose since 2004,” he told AAP.

Mr Feeney was state secretary for the Victorian ALP from 1999 until 2002 and received donations from the tobacco company for the party in his capacity as a fundraiser.

Philip Morris labelled the claims “completely false”, with a company spokesman saying no such donations were ever made.

Several unions and opposition leader Bill Shorten also donated to Mr Bolano – across factional lines – following a split of the Victorian ALP right.

Mr Shorten donated $5000.

Ms Jackson, who faces allegations of rorting more than $1.2 million in members’ funds, is due to give evidence later in the week.