A delay has occurred during the pre-season trial match between the South Sydney Rabbitohs and Manly Sea Eagles, with reports indicating a fan has suffered a heart attack.

The match was scheduled to begin at 3:30 pm at Industree Group Stadium at Gosford before a supporter inside the venue suffered a heart attack but has now been confirmed to start at 5:10 pm.

Paramedics rushed to the aid of the supporter as they were on standby for the trial match.

Under the NRL guidelines, the match cannot start until the paramedics return to their post.

The Rabbitohs and Sea Eagles were kept inside the changing rooms, waiting for clearance from the authorities.

It is understood that the match could be abandoned.

The league has reportedly put a call out to an independent paramedic to assist with the health emergency in order for the game to proceed.

"It's very sad and tragic," Mal Meninga said onย Fox League.

"I've been around rugby league for a long time and I've never experienced anything like this."