A crocodile that bit a man on the head could have been stalking boats near a popular natural tourist attraction in Western Australia’s north for months, authorities say.

A saltwater crocodile, up to three metres long, attacked two men in Cyclone Creek, at Talbot Bay in the Lalang-Gaddam Marine Park on Monday.

The pair who work for a luxury tour company which ferries tourists by plane and boat to the Horizontal Falls, north-east of Broome, were crabbing at the time of the attack.

A caller to 6PR Perth identified himself as the father of one of the victim’s friends on Tuesday morning.

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“A croc leapt out and grabbed one of them by the head apparently,” he said he was told by his 18-year-old son.

The man said his son’s mate who was in the tinnie with him, a quick thinker, grabbed a knife and stabbed the croc in the head with a knife.

“The croc let go … apparently he’s fine.”

WA’s Department of Biodiversity, Conservation and Attractions said it may not be the first time the crocodile has attacked.

“Earlier this year, a similar-sized crocodile was reported launching itself towards vessels at this location,” a spokesman said.

An alert, warning tour operators and visitors to be cautious about crocodiles in the area has been in place since.

Parks and Wildlife Service rangers were travelling to Talbot Bay to patrol.

If a crocodile matching the description of the one involved in Monday’s incident is found it may be removed if it continues to pose risks to public safety.

Their employer Horizontal Seaplane Adventures said both men were undertaking personal activities outside of work hours on a boat not used by guests when the incident occurred.

The men were flown to Broome Hospital for assessment and treatment after the The Royal Flying Doctor Service WA provided advice over the phone.

-AAP