The NRL has provisionally suspended off-contract Brisbane Broncos hooker James Segeyaro under the league's anti-doping policy.

It is alleged that Segeyaro returned a positive A-sample for di-hydroxy LGD-4033 which is prohibited by the World Anti-Doping Agency.

LGD-4033 is a non-steroid agent that is popular among bodybuilders for its muscle mass increasing properties.

He was tested by the Australian Sports Anti-Doping Authority on September 3rd and will be prohibited from playing rugby league while the suspension is in place.

He also prohibited from participating in any other WADA governed sport.

The NRL made contact with Segeyaro after ASADA advised them of their findings on Thursday afternoon.

He will be given opportunity to have his B-samples tested in light of the initial positive test.

"Under the anti-doping policy, Mr Segeyaro now has the opportunity to have his B-sample analysed," an NRL statement said.

Segeyaro was a late inclusion in coach Anthony Seibold's squad having joined as a mid-season recruit from Cronulla after their salary cap woes forced him to start the year playing in the NSW Cup.

He was was forced to find work as a barista to sustain himself while confined to reserve grade.

Di-hydroxy LGD-4033 is the same substance that has been found in Australian swimmer Shayna Jack, who faces a ban of up to four years.

The Broncos said on Thursday night they were still trying to get in contact with Segeyaro who is overseas on an end of season holiday.

"The Broncos have been working closely with the NRL since being alerted to the positive test early this evening," a Broncos statement said.

"With athletes unable to participate in any WADA-compliant sport while an investigation of this kind is underway, the player has been immediately stood down.

"Under due process through the anti-doping policy, the player now has the opportunity to have his B sample tested.

"As this matter is currently an active investigation, the Broncos are unable to make any further comment.

Segeyaro - a nine season NRL veteran - will remain sidelined as he sweats on his future.

He looks set to miss this month's World Cup Nines after being named in PNG's squad this week.

The A-sample results came the same day reports emerged salary cap pressures looked set to squeeze Segeyaro out of Brisbane next year.

-with AAP