A Senate economics inquiry in Melbourne on Wednesday will also question fellow spruiker Jamie McIntyre, currently the subject of a separate ASIC investigation over a string of land-banking schemes across Victoria. The committee is probing advice on, and marketing of, land-banking as part of an ongoing inquiry into financial advice.

Land-banking involves buying outer-suburban land before it has been slated for redevelopment, and benefiting from a future lift in value. But in the case of the Kaye projects, investors did not buy actual land, they bought "wholesale options" which, in reality, were simply a right to buy a stake in the promised developments at a certain price. It's unclear if those developments will actually take place.

The Senate and ASIC land-banking inquiries were triggered by Fairfax Media revelations earlier this year about proposed luxury developments across Victoria based on the contentious "wholesale" property options.

The schemes, most of which are earmarked for sites on the outskirts of Melbourne and regional Victorian cities, have affected thousands of Australian investors.

Senator Nick Xenophon, who has pressed for action on the schemes, said: "The inquiry was driven by concerns about gaping holes in our legal framework when it comes to property spruiking, holes through which hundreds, and possibly thousands, of Australians have already fallen. We need to ensure no more do."

However the committee has failed in its efforts to have the elusive Kaye and key associates appear before it.

"I don't believe this inquiry will be complete until Henry Kaye and his key business associates appear," said Senator Xenophon. "There are matters we want to discuss with Mr Kaye and his associates which are very much in the public interest."

The Belarus-born Kaye first came to prominence in the early 2000s as the head of a get-rich-quick property empire that targeted unsophisticated investors. It collapsed in 2003 owing 3500 investors up to $60 million.

He was later found by the Federal Court to have breached the Trade Practices Act, and in 2010 was barred from managing companies for five years. The ban ended in July.

ASIC will also be questioned on Wednesday about its inquiry of Kaye, McIntyre, his brother Dennis, seminar organiser Global 1, and lawyers Darren Eliau and Ben Skinner from legal firm Evans Ellis.

In March, Fairfax confirmed a direct role by Kaye in the first of a string of land-banking projects, this one in regional Shepparton. Since 2010, companies Market First and 21st Century have sold options and land packages in proposed luxury estates, often on farmland not yet approved for development. Kaye's sister Julia Feldman has been a key player in both companies.

Fairfax Media also understands that Victoria's legal watchdog, the Legal Services Commission, is investigating the role of at least one lawyer associated with the schemes, former Slater & Gordon senior associate Adam Zuchowski.

Sales company Market First recommended Slater & Gordon to customers buying into projects at Truganina and Melton in Melbourne's west.

In January, Fairfax revealed that Slater & Gordon withdrew after an internal probe raised concerns about the secrecy around the individuals behind the schemes. The law firm wrote to scores of clients warning their investments could be at risk and suggesting they seek independent legal advice.

Fairfax Media is aware that during an internal investigation of its involvement in the schemes, ASX-listed Slater &Gordon grew concerned that Mr Kaye and/or his family may be involved.

Property spruikers Market First Property Consulting featured the Slater & Gordon brand in get-rich property seminars, including in Melbourne, Sydney and Perth.

Market First documents obtained by Fairfax revealed a managing partner was Julia Feldman, the sister of the Belarus-born Henry Kaye.

Ironically, it was Slater & Gordon, a company renowned as the legal champion of ordinary Australians, that ran a class action by disgruntled property investors against Kaye after his property empire collapsed.

The mainstream development industry has warned investors about purchasing options in future housing estates that may never be built.

Market First and its spruikers have made grand claims about the proposed estates on Melbourne's western perimeter, traditionally one of the city's more affordable and humble housing locations.

"Veneziane", earmarked for the backblocks of Melton, was spruiked in marketing material as an "iconic architectural masterpiece" featuring a resident-only helicopter service, waterfront wellness retreat, private gold class cinema room and a "secluded terrace oasis".

One unhappy investor in another of the schemes, known as Foscari, who attended a Market First get-rich seminar, said attendees were repeatedly reminded of Slater & Gordon's involvement.

"That was our assurance; that a reputable firm that had a reputable name in the community was involved in it ... that's the one thing that sold me," the investor said

Slater & Gordon has refused requests by Fairfax Media for an interview about its involvement in the schemes.