An American scoutmaster is recovering after being mauled by a black bear which dragged him into its cave.

Christopher Petronino, 50, told authorities he hit the animal with a hammer and played dead before summoning help.

The bear grabbed the New Jersey man on Sunday as he was showing his son and two other scouts, ages 12 to 14, a cave that he regularly visits at Split Rock Reservoir in Kinnelon, west of New York City.

Mr Petronino entered the cave, which he thought was empty, when the bear grabbed his foot and pulled him further inside, New Jersey Department of Environmental Protection spokesman Bob Considine said.

Mr Petronino suffered bites and scratches on his head, shoulders and leg, authorities said.

They said he tried to fend off the bear, hitting it twice in the head with a rock hammer.

"The man fought back," New Jersey Division of Fish and Wildlife director Dave Chanda said.

"It appears he played dead for a little bit."

The bear was defending a cave where it was spending the winter, authorities said. ( stock.xchng: mazwebs )

Mr Petronino then pulled his jumper over his head and curled into a foetal position. He yelled to the scouts to get help and to place any food they had at the cave entrance to lure the bear out.

None of the scouts were injured. They used a mobile phone to alert authorities and tied bandannas to sticks to help rescuers find them.

The bear eventually left the cave and then escaped.

Authorities said it would not be pursued for capture.

"It was just defending an area that it set up to spend the winter," Mr Chanda said.

Authorities praised the scouts for aiding in the rescue of their scout master, who was treated at a local hospital.

Officials said hikers should not enter caves, particularly during bear hibernation season, and should not use food as a lure with bears. They also said that anyone who is attacked by a bear should fight back but not play dead.

The attack occurred as New Jersey's extended bear hunt came to a close on Saturday, with 510 bears killed by hunters since December 7.

Wildlife officials widened the annual hunt after numerous bear sightings in populated areas and the fatal mauling of a college student hiking in September 2014.

Bear attacks have been making news in the US recently, with an upcoming film starring Leonardo DiCaprio featuring a scene where the actor is brutally mauled.

DiCaprio told ABC's 7.30 the scene involved months of rehearsal and that director Alejandro González Iñárritu watched footage of "100 different bear attacks".

"What he achieves cinematically is something that I think is very ground-breaking, and that is the ability for an audience to be in a sort of very raw, violent, savage bear attack, yet feel the intimacy of both man and beast," he said.

Reuters/ABC