All Bulldogs first grade players might have to provide DNA samples as part of an investigation into the alleged sexual assault of a woman in Coffs Harbour.

And the National Rugby League warned any player found to have committed a criminal offence could be thrown out of the game, with the club fined up to $1 million.

Coffs Harbour police are continuing their investigations into the alleged assault, which occurred on Sunday morning in the NSW coastal town where the club was playing a pre-season trial.

Police have already spoken to four players and are expected to arrive in Sydney in the next fortnight to interview more of the Bulldogs squad.

Police said there was no video evidence of the incident and wouldn't rule out using DNA as part of their investigations, which could take several months to complete.

"DNA may form part of the investigation," Detective Gary McEvoy said.

"DNA is a lengthy process and takes some time.

"We were saying this may well take weeks, or months, particularly if it's going to rely on DNA evidence."

Bulldogs players aren't the only party in police sights over the incident.

They said criminal charges could be laid after details from a police report were leaked and aired on radio.

Brought to you by AAP © 2024 AAP