THE NRL has offered to help Melbourne explore ways to prevent Greg Inglis from switching to rugby union but it will not bend the rules to keep him the game.

Amid reports of Inglis's growing interest in a code switch and French rugby union clubs circling, the Storm have asked the NRL for assistance.

NRL boss David Gallop confirmed he had held discussions with Storm chief executive Brian Waldron about ways to increase Inglis's earnings but said the league was limited to introducing him to potential sponsors.

Gallop ruled out allowing any salary cap exemptions or offering direct financial assistance despite an alarming trend of the game's elite players, including Sonny Bill Williams and Mark Gasnier, being enticed overseas.

"We're happy to talk to them about potential relationships with our sponsors but we've made it clear there can't be any exceptions to the salary cap rules," Gallop said.

"We're just introducing him to our sponsors, which is really the only measure we can do."

Fears the Kangaroos and Queensland star could jump ship have intensified since he talked about linking up with Anthony Mundine and Khoder Nasser - the duo behind Williams's defection.

There have also been reports that Inglis had already spoken to his parents about a move overseas and got their blessing. Inglis has two more years on his deal but Melbourne would struggle to offer him the $500,000 or so he is likely to demand when it expires.

It means Inglis's earnings would need to be topped up by a third-party sponsorship deal, similar to that arranged for Gasnier with the Dragons.

"It's something that we regularly do with elite players," Gallop said.

"Sometimes there are sponsors willing to get on board with them, but it's very important that we don't make an exception to the rules. We can't start making exceptions for certain players."

Gallop said the NRL would investigate other ways to encourage top-line talent to remain in Australia but ruled out a centralised contract system like the ARU or Cricket Australia because it did not work with a salary cap system.

He did, however, hint an increase in representative payments for Test and State of Origin players could be on cards for next season.

Meanwhile, Souths have declared their investigation into last Sunday's socket throwing incident closed despite being unable to identify the culprit through interviews and CCTV footage. Manly centre Steve Matai was the target of the small metal object as he was sinned during his side's shock loss to Souths.