Mining magnate Gina Rinehart is believed to have lifted her stake in Fairfax Media, and questioned the abilities of the company's chairman Roger Corbett in the process.
The world's richest woman was last week overlooked for a Fairfax board seat, in favour of former Ernst & Young boss James Millar.
But that has not appeared to dampen her interest in the embattled media company, which is in the middle of a cost-cutting drive to offset declining newspaper sales.
Fairfax's Sydney Morning Herald website on Monday reported Mrs Rinehart had increased her stake in Australia's second biggest newspaper publisher to more than 13 per cent from the 12.8 per cent holding she bought in February.
In a statement to the website, Mrs Rinehart confirmed her company, Hancock Prospecting, had lifted its stake in Fairfax as she took aim at Mr Corbett.
"There are questions to be raised concerning the current chairmanship that has presided over both an approx. 60 per cent loss in share market value and continuous loss of circulation of all (its) major mastheads, which in turn (affects) revenue," Mrs Rinehart's statement said.
"Answers need to be given as to how the chairman will address this in the interests of all shareholders, rather than merely hoping for improvements in circulation, revenue and share price or perhaps trying to blame ... industry conditions."
Mrs Rinehart is understood to have requested two board seats at Fairfax after becoming the newspaper publisher's largest shareholder earlier this year.
In her statement, Mrs Rinehart said it was too early to say if Hancock Prospecting would hold its 13 per cent stake in Fairfax.
Fairfax shares, which are trading around record lows, were one cent higher at 63.5 cents at 1.00pm..