A man has died after being attacked by a shark off the coast of the north-eastern Australian state of Queensland, police have confirmed.

Emergency services were called to a boat ramp on the Cassowary Coast, between the cities of Cairns and Townsville, just before noon local time on Sunday, following reports of a 39-year-old being attacked.

Queensland Police said that the man was retrieved from the water but later died. He was believed to have been spearfishing near an offshore reef.

In that incident, the man had been bitten on the lower legs and could not be revived.

Queensland Police has not disclosed the latest victim's identity.

It said it would now prepare a report for the coroner on the "sudden and non-suspicious" death.

Later Police Inspector Elaine Burns told reporters that the man, along with three others, had taken a private vessel to Kennedy Shoal, a shallow reef about 45km (28 miles) off the Queensland coast.

"We believe the man had been spearfishing when he was attacked and died from a critical head injury," she said. "He was retrieved from the water by another person who was in the water with him at the time of the attack."

He was declared dead when they reached shore about an hour later, Burns said.

"That's quite a terrifying thing to see happen in front of you," she said, adding that police were providing what support they could to the man's three companions.

Shark attacks around Australia are more common than in many other parts of the world, though they are often not fatal.

There were four encounters with sharks across Australia in January, according to the Australian Shark-Incident Database, only one of which was fatal.

Popular swimming and surfing spots tend to have measures to protect against attacks.