Manly's Lottoland could lose Saturday's home final against Cronulla after asbestos were found on the hill, according to The Sydney Morning Herald.
A safety assessment will be conducted on Monday, with the potential to move the game to Bankwest Stadium.
The NRL will withhold ticket sales for 24 hours.
NRL boss Todd Greenberg said the safety of fans was the number one priority.
"Our number one priority is ensuring the safety of our players and fans. Unfortunately it could not be guaranteed when the schedule was confirmed," Greenberg said.
"We have given the local council and the Sea Eagles a period of grace of 24 hours in order to assess the safety of the venue before we release tickets.
"We have worked with Northern Beaches Council and the Sea Eagles to ensure the club is given the opportunity to host a Final, while ensuring the safety of our supporters is paramount."