Revelations that drug use is rife in Australian sport and linked to organised crime have concerned major rugby league sponsor Telstra, with the telcoms company hinting it could reconsider its support.

The Australian Crime Commission on Thursday identified common use of prohibited substances across multiple sporting codes, shocking the nation.

Telecommunications giant Telstra, which has a naming-rights deal with the National Rugby League worth more than AUS$100 million (RM318 million), said it would look closely into the report, which also found links to organised crime.

"Our brand image is very tightly tied up with those who we sponsor so if there is untoward behaviour that we don't agree with, we make our position very clear, so we'll always do that," said Telstra chief David Thodey.

"Our brand position is very important in terms of being aligned to properties that we share the value with."

But John Tripodi, chief executive of business marketing consultancy Twenty3, said sports sponsorship contracts may not be easily broken, with "get-out" clauses often not mentioning drugs.

"Those get-out clauses are not as widespread as people think," he told the Australian Financial Review.

"Sponsors want public interest and eyeballs, and sport delivers that to them."

The crime commission report did not name specific players, teams or codes due to legal reasons but rugby league chiefs admitted the sport was under scrutiny.