Bain added the rival offer was actually designed to “frustrate the administration process by creating as much noise and interference as possible”.
The revelation came despite them losing a Federal Court case on Friday to gain access to secret details of Bain’s ‘winning’ proposal.
The move comes days after the group also asked Australia’s takeover watchdog to intervene because they weren't allowed to present their plan to creditors.
Broad Peak Investment Advisers and Tor Investment Management, representing the bondholders, are seeking an interim order to allow their own offer to be put to creditors ahead of a vote in August.
Bain Capital has reacted to news the airline's bondholders have launched an 11th-hour bid by making a series of new promises to staff.