Members of a fund-raising body associated with Federal Treasurer Joe Hockey have been invited to pay $3000 to go to a budget day event with his senior staff and ministers.

This comes just two days after revelations Mr Hockey met with business people at his parliamentary office in return for donations to the Liberal Party.

The revelations triggered calls from former Liberal leaders Malcolm Fraser and John Hewson for donation reform.

Fairfax reports the North Sydney Forum, which offers exclusive access to Mr Hockey in exchange for an annual membership fee of up to $22,000, sent the invite to the May 13 event in February.

The Forum is a campaign fundraising body run by Mr Hockey’s North Sydney Federal Electoral Conference (FEC), which says its membership list, and therefore donor identities, are “confidential”.

The event will feature pre-budget briefings, lunch at Parliament House and dinner in the Great Hall.

Attendees will hear Small Business Minister Bruce Billson, Mr Hockey’s chief economic advisor Tony Pearson and economist Ian Harper discuss “Australia’s Economy Now and into the Future”.

Fairfax claims the invite was sent by chairman of the North Sydney Forum John Hart who is also chief executive of hospitality industry group Restaurant and Catering Australia.

Monday’s revelations have triggered calls to reform political donations in Australia notably from former Prime Minister Malcolm Fraser.

Mr Fraser said it was “very likely” a federal version of the NSW Independent Commission Against Corruption was needed.

He told Fairfax while he was certain Mr Hockey was “totally honest”, the system that had developed around donations was abhorrent.

“If you go back to the [predecessor to the Liberal Party, the] United Australia Party, the people who funded the party thought they could control policy,” Mr Fraser told Fairfax.

“Menzies was determined that that would not happen.

“Public funding and banning private donations to political parties is not necessarily a simply solution…the easier thing is to establish total transparency, and to have that transparency immediate, reporting weekly or every few days.”

Mr Fraser tweeted that this type of situation “used not to happen” and that “cash for chat is corrupting our democratic integrity”.

Mr Hewson called for continuous disclosure, and said declaring donations every few days would “create a different climate”.

“My preference is to ban all donations by organisations, companies, associations, unions and research bodies, and then limit individual donations to a low maximum. And we need immediate disclosure of donations.”