Deputy Prime Minister Julia Gillard says it is up to the NRL - and not the government - to investigate claims of widespread salary cap rorting.

Former Melbourne Storm chief executive Brian Waldron has called for a public inquiry into rorting of the salary cap, saying numerous NRL clubs had been involved in cheating the system over many years.

The Storm were stripped of the 2007 and 2009 premierships and banned from earning competition points in the 2010 season, after the club was caught paying $1.7 million over the salary cap.

Ms Gillard, a Storm supporter, said it was important the NRL and News Limited ensured any investigations into rorting of the system were thorough and transparent.

"Right across the code, people's confidence has been rocked, so there is a need to restore trust in the game and a common adherence to the rules," Gillard said on Wednesday.

But the deputy prime minister said it was not for the government to set up an inquiry.

"However I don't believe there's a role for government in this investigation.

"This is something I'm confident the NRL can deliver."

Ms Gillard said she would be sticking by the Storm despite last week's revelations.

"We've got to stay the journey with the Melbourne Storm. That's certainly what I intend to do," she said.

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