South Sydney coach Michael Maguire has called on the NRL to investigate why Canterbury skipper James Graham was allowed to return to the field after suffering a severe concussion.

Graham showed signs of balance disturbance after copping a knee to the head in an attempted tackle on Tom Burgess in the opening minute of the second half.

The Bulldogs prop staggered to his feet and tried to wave away the trainer before coming off for a concussion test.

The England international returned ten minutes later to help stem a mini Rabbitohs comeback before the Bulldogs eventually prevailed 32-18.

Maguire said the governing body needed to investigate whether the Bulldogs had abided by the new guidelines.

“There’s rules in place in the game, I’d like to think we’d make sure they’d go through those,” he said.

“The concussion rule is there and the game has to adjudicate that and how they saw it.”

Graham denied being concussed, explaining that he only came off for precautionary measures.

“I wasn’t concussed,” he said.

“Obviously I showed signs of a concussion. But I came in, did the test, passed, and I was allowed to return back to the field okay.”

The NRL tightened its concussion laws back in April, stating that a player must not return to the field if he exhibits ‘ataxia’, commonly known as balance disturbance.

“As far as I know, that’s the rule,” Maguire said.

“Again, it’s in the game’s hands.”

Bulldogs prop Tim Browne was also forced from the field in the first half after taking a knock to the head, but failed the scat test and didn’t return.