Mafia figures donated tens of thousands of dollars to the discredited NSW Liberal Party fundraising vehicle, the Millennium Forum, as part of an ultimately successful campaign to allow a known criminal to stay in Australia.

A senior Millennium Forum figure, who is already under investigation by ICAC for allegedly funnelling illegal developer donations to the NSW Liberal Party, also helped criminal Frank Madafferi's lawyer meet then immigration minister Philip Ruddock on the visa issue.

A year-long Fairfax Media and Four Corners investigation has obtained confidential documents that outline the Millennium Forum's role as the receiver of the Mafia money, raising more questions about the integrity of the nation's political donations regime.

Documents also reveal that Victorian Liberal MP Russell Broadbent hosted alleged Mafia boss Tony Madafferi, Frank's brother, for lunch in the parliamentary dining room and in his Parliament House office. Mr Broadbent also introduced Tony Madafferi and his associates to senior Liberal MPs including Environment Minister Greg Hunt.

Mr Broadbent, who has repeatedly refused to answer questions, helped organise, or attended, several fundraisers involving the alleged Mafia figure.

It can also be revealed that Sydney furniture king Nick Scali, a prominent Liberal donor and Madafferi associate who was also involved in the Mafia visa scandal, was investigated by police in Italy over allegations that he bribed an Italian-Australian politician in Rome.

ICAC counsel assisting Geoffrey Watson SC and former Millennium Forum and federal Liberal Party treasurer Michael Yabsley have now both called for Australia's political donation system to be overhauled.

Mr Watson, who led last year's ICAC public hearings into the forum's dealings with property developers, said the new revelations showed the entire fundraising system was "seriously" compromised.

And Mr Yabsley, who once chaired the Millennium Forum but who is not the figure involved in the Madafferi lobbying, said donations should be capped and all entities banned from making them.

"The system is wide open to the kind of abuse by criminals and their representatives," Mr Yabsley said.

"The more common problem is where donors actually have an expectation of some kind of policy or other outcome in view of their donation."

The former head of the Millennium Forum, Paul Nicolaou, confirmed on Monday that, "The NSW Liberal Party and the Victorian Liberal Party received 50 per cent [each] of the proceeds from that fundraiser".

"I don't know who was at the function and who the people were. There were several hundred people at the event."

On Monday, Fairfax Media and Four Corners revealed confidential police assessments warning that alleged Mafia figures had infiltrated federal and local politics via the donations system.

One of the police assessments dealt with a political lobbying and donations campaign run by the Madafferi brothers, aimed at overturning Frank Madafferi's deportation, which was ordered in 2000 by Mr Ruddock.

Mr Ruddock's successor as minister, Amanda Vanstone, granted Mr Madafferi a visa in November 2005, despite his lengthy criminal record and police warnings he posed a risk to the community. Less than two years later, he was implicated in the world's biggest ecstasy shipment and in 2008 he was arrested, and later jailed, for drug trafficking.

As part of the visa campaign, prominent Liberal donor and occasional Labor Party supporter Mr Scali arranged a meeting in October 2001 between Tony Madafferi and a prominent Liberal Party figure involved in the Millennium Forum.

The Millennium Forum figure then facilitated a meeting between Frank and Tony Madafferi's personal lawyer and Mr Ruddock. The meeting gave the Madafferi family direct access to the immigration minister to discuss the deportation order.

Liberal Party sources said Mr Ruddock was furious when he realised the Madafferis' lawyer had been granted a meeting with him. The meeting between Mr Ruddock and the lawyer was cut short and Mr Ruddock refused to budge on the deportation.

In September 2004, with the visa campaign in full swing, the Millennium Forum in NSW received $51,000 in declared donations from Tony Madafferi and his associates in connection to a political fundraiser he organised in Melbourne. Thousands more in undeclared funds were collected via raffle tickets and other techniques during the fundraiser.

This event was attended by new immigration minister Ms Vanstone and three Liberal MPs who had, after approaches from Madafferi linked donors, raised the visa case with Ms Vanstone.

Mr Watson said the Madafferi visa campaign showed how "for no better reason than the making of donations to a political party, specific representations were able to put to amongst the most powerful politicians in the land."

Ms Vanstone has said her decision to give Frank Madafferi a visa was based on humanitarian grounds linked to the impact of deportation on his family.

But Mr Ruddock told Four Corners that he stood by his deportation order and that "the Australian public expect" the politicians would not "give preference" to criminals seeking visas.

"In this matter… there is a serious criminal record. The view that I formed was that on the basis of the criminal record, he should be deported."

Mr Yabsley's comments about the need to overhaul the donation system are especially impactful as he once headed the Liberal Party's fundraising arm.

"The whole spectre of political donations casts a shadow over our relatively clean and accountable democratic system," said Mr Yabsley.

"It wouldn't be the first time someone has seen the light from working on the inside and set about to fix something that has caused them great and increasing concern the more they saw of it."

The release of the ICAC report into the Millennium Forum and other Liberal fundraising vehicles has been deferred due to legal challenges. Tony Madafferi denies any wrongdoing and has not been convicted of any criminal offence.