Image caption Australia's Northern Territory has a big population of saltwater crocodiles

Police say they have found the body of a man snatched by a crocodile as he swam in a river in Australia's Northern Territory during a birthday party.

The body of Sean Cole, 26, was found on Monday in the area where he was last seen.

Police say he ignored signs to stay out of the water at a popular camping ground at Mary River, 65 miles (100km) from Darwin, the territory's capital.

The river has one of the highest crocodile populations in the area.

Onlookers watched in horror as the victim was suddenly attacked.

The victim and another man had gone swimming across the river, and were swimming back when the crocodile attacked, police said.

"Several of the group in the party witnessed the male being taken in the jaws of the croc for a period of time, and then he was out of sight," Senior Sergeant Geoff Bahnert was quoted as saying by the AP news agency.

"The Mary River is known worldwide to have the greatest saturation of adult saltwater crocodiles in the world. You don't swim in the Mary River," he added.

At least four crocodiles have been shot in the area following the incident, rangers say, including one believed to be responsible for Mr Cole's attack.

Saltwater crocodiles can grow up 7m (23ft) long and weigh more than a tonne. They are a common feature of Australia's tropical north.