Health Services Union national secretary Kathy Jackson has told the royal commission into union corruption that she has been destroyed politically by allegations of corruption levelled against her after she blew the whistle on widespread corruption at the union.

Ms Jackson is giving evidence before the Royal Commission into Trade Union Governance and Corruption.

The commission is investigating allegations she was involved in a union slush fund account and that members’ money was used to pay off her personal credit cards.

Ms Jackson told the commission she was conflicted when she first began to have suspicions about the union’s accounting in 2010 and 2011.

“I was friends with these people. When you work in the union movement, you make friendships. It’s a community,” she said.

Ms Jackson exposed the corruption within the union’s Sydney base involving senior officials Craig Thomson and former HSU general secretary Michael Williamson, who is now in prison.

She said her suspicions crystallised during a working meeting at Williamson’s holiday house.

“There was no way, from what I knew at the time, that Mr Williamson could afford to live in such a palatial holiday home and have the mod-cons available to it,” she said.

“I think he had plans there as well – this in-ground swimming pool was going to be built. And there was going to be a cabana and all this other stuff – there were jet skis out on the lake.”

But she said she was very wary about raising her allegations until she had further information.

“It dawned upon me after that visit, seeing what I saw and seeing some the behaviour of the people there, that something had to be done. But I knew that if I did something, it wasn’t an easy thing to do, because they’d be after me.”

Yesterday, the commission heard evidence that a $250,000 settlement for underpaid workers was transferred from the HSU into Ms Jackson’s slush fund, called the National Health Development Account.

But Ms Jackson said she had been targeted for speaking out.

“I’m here telling the truth – I’ve always told the truth. And here I am as a target, not by the membership, but more importantly a target by the media, a target by the ALP and the Labor movement, which I knew would happen, but I’d never thought it would happen this badly.”

The hearing continues.