NRL CEO Todd Greenberg.

NRL chief executive Todd Greenberg won't be given names of players or officials that have been pivotal to police investigations into match-fixing, but believes the probe into illegal activity will help safeguard the sport.

The NRL is keen to find out the names of some of the individuals that were key figures in the police investigations, however the crime authorities are bound by legal obligations that prohibit the exchange of such information, despite no charges being laid.

"Police are under difficult circumstances for what they can and can’t say to us," Greenberg said.

"We're shrouded behind a legal controversy here … We've asked for as much information as we can possibly get because the more information we have, the better informed we are of the challenges we face."

Greenberg fronted the media in Melbourne on Friday on the day of the World Cup opener to discuss the investigation which closed this week with no charges laid.

However, police did establish links between NRL players and crime figures known for drug trafficking and money laundering.

Police found no evidence of match-fixing and Greenberg believes the investigation and the code’s cooperation with the police will be valuable for the sport.

"We've been cooperating with police continuously for the best part of two years … as we should do," Greenberg said.

"When allegations like this surface either through the media or the public domain, we're very keen to make sure they are tested and that’s what we’ve done with the police over a long period of time. To be honest, this investigation will hold us in good stead in the coming period of time.

"People will know that despite a very intensive investigation, the game has not been charged and players in the game have not been charged and that’s a very important step in this journey."

The NRL has invested millions of dollars into its integrity unit in recent years, making a conscious effort to restrict the opportunity for players and officials to exploit the sport.

"We've made some significant changes about the rules and regulations of wagering," Greenberg said.

"The work we've done in our integrity and the way teams are named – some of these changes have been quite systematic with our integrity unit over the past 12 months. An enormous number of lessons, and never should anybody think we will ever get complacent about the challenges inside the sport and in particular, challenges inside society.

“What I took out of a lot of what the police comments were today is that a lot of these challenges flow across our community and all sports, not just the NRL. But we won’t be complacent and we’ve shown over time that we will act if, and when, we need to and update and change rules.”

The revelations have overshadowed the opening day of the World Cup, with Australia and England set to lock horns at AAMI Park on Friday night.

“This is not my choosing, the timing today,” Greenberg said. 

“Clearly if I had my own choice of timing I wouldn’t be doing it at the start of the World Cup. But I’m a realist and I understand the demands of police authorities in NSW and around the country. While I would prefer to be talking about the Rugby League World Cup today, I understand that some of these timings are out of our control.”