It came after the administrators of Great Southern's collapsed rival, Timbercorp, called for all 41 companies in the group to be wound up, pointing to the "extreme" complexity of the Timbercorp group and its "significant and immediate" need for cash to keep operating.

Late on Friday Great Southern responded to a fax the stock exchange sent nine days ago that highlighted the group's disclosure of yields from two plantation projects, and Mr Young's sale of 7 million shares in the company on February 17, 2005.

Among its 22 questions levelled at Great Southern, the stock exchange asked whether "significantly lower yields" in two early plantation projects were material to the company, when Great Southern became aware of the lower yields, and whether premiums paid to investors - in addition to how much the timber would fetch on the market - was material to the company.

It asked whether Great Southern had breached listing rules by not disclosing material information.

Great Southern's 2005 annual report, made public in September that year, notes the 1994 project produced "significantly lower yields" than were originally projected and that a premium had been paid to investors on July 29 to make up the shortfall.

Mr Young's share sale was mentioned in a Great Southern company announcement that same day, and was the subject of a formal ASX directors' notice four days later.

In response to this month's inquiry from the stock exchange, Great Southern's secretary, Neil Hackett, denied on Friday that the low yields were material and said yields from earlier projects were "not directly relevant" to projects established later.

He also argued the lower-than-expected yields from early eucalypt plantations was "generally known and documented within the industry" and said growers were sent forester reports in 2001 and 2002 noting the impact of drought on the plantations.

The company had complied with listing rules "to the best of its knowledge", he said.

Great Southern, which sold tax-effective investments based on agri-business projects such as bluegum plantations, collapsed last month. Timbercorp suffered the same fate weeks earlier.

Timbercorp administrator KordaMentha on Friday set out the factors behind the group's demise, including drought, dwindling sales of its managed investment scheme products and rising defaults by Timbercorp investors on loan repayments.