Landmark White said on Thursday it had suffered another data breach, with valuation and operational documents posted to website SCRIBD in what it suspected was a deliberate act of sabotage by a known person.

The troubled valuation firm, which earlier this month said it would post a net loss after tax of $2.3 million this year as the result of an earlier data breach that made its lender customers suspend it and caused chief executive Chris Coonan to resign, disclosed details of the second breach in a statement after  the ASX had closed.