THE NRL has demanded the Sydney Roosters explain the presence of Essendon’s former sports science boss on their players’ bench at Suncorp Stadium on Friday night.

Dean Robinson, the high performance chief at Essendon during their peptide scandal, was spotted on the bench and sitting among the coaching staff during the loss to the Broncos.

“We’ll ask for an explanation from the Roosters,” said an NRL spokesman. “Unless he’s registered he would not be allowed in that area.”

Known in AFL circles as ‘‘The Weapon’’, Robinson is the brother of coach Trent Robinson and was sacked by the Bombers when the club initially self-reported to the AFL for the use of banned substances in 2012.

The ASADA investigation into Essendon found Robinson sourced two banned peptides and a form of human growth hormone from sports scientist Stephen Dank. He admitted to taking injections himself.

Colleague Rebecca Wilson first questioned Robinson’s presence at the Roosters a fortnight ago. At the time we checked it out with CEO Brian Canavan, who denied Robinson was working for the club, though he admitted he often spoke to his brother about training and sports science issues.

HOODOO: Pearce’s Suncorp nightmare

media_camera Dean Robinson with Mitchell Pearce on the Roosters bench.

Just after halftime on Friday night, Wilson texted me a shot of Robinson on the Roosters’ bench behind injured half Mitch Pearce. The pair had a short conversation.

He was wearing a lanyard with official NRL accreditation as a Roosters representative, allowing him dressing-room access.

I sent the photo to NRL media boss Peter Grimshaw to get an explanation. Under NRL rules, all coaching staff members must be accredited and registered.

Canavan was still denying Robinson’s involvement with the club when contacted on Saturday.

“Trent just wanted him there,’’ Canavan said. ‘‘There’s nothing he’s doing with the club in a formal way.

“It’s just brotherly support.”

Asked if it was a bad look to have Robinson on the bench, Canavan said: “I suppose we didn’t know where to put him. We get lanyards issued by the NRL to get people in the dressing room area. He got one so he could be around Trent — that’s all it was.”