A $75,000 third-party arrangement for former Parramatta superstar Jarryd Hayne is believed to form part of an NRL probe into the club's salary cap and corporate governance practices.

As reported by Fairfax Media, the governing body is investigating whether the Eels fully disclosed a TPA to Anthony Watmough by a company that is directly related to the club. The issue relates to an alleged failure to properly declare that Watmough's sponsor, ScoreCube, is a wholly owned subsidiary of BlackCitrus, a company that provides a number of IT services to the blue and golds.

It has emerged that ScoreCube also sponsored Hayne to become an "ambassador" in a transaction likely to pique the interest of auditors at Rugby League Central.

The NRL approved both TPAs at the time, but it's understood head office is investigating whether the club properly disclosed any potential conflicts of interest. Salary cap rules forbid firms in commercial relationships with the clubs serving as a TPA sponsor and the onus is on officials to provide full disclosure.