A desperate search is underway in northern Australia for a child feared to have been taken by a crocodile.

The 12-year-old was last seen around dusk on Tuesday, swimming near the remote town of Nganmarriyanga - about a 7-hour drive southwest of Darwin in the Northern Territory (NT).

Police say a specialist search and rescue team has been deployed after "initial reports stated the child had been attacked by a crocodile".

The NT is home to an estimated 100,000 saltwater crocodiles, more than anywhere else in the world, but attacks are uncommon.

Community members in Nganmarriyanga - previously known as Palumpa and home to only 364 people - and local police began searching for the child immediately after they vanished in Mango Creek around 17:30 local time (08:00 GMT).

They have now been joined by additional officers and the expert search and rescue team who are combing over both land and water.

An aerial search may also be launched, according to local media.

NT Police Minister Brent Potter on Wednesday afternoon said the operation had entered the "recovery phase".

"It's a tragic incident for any parent or family member to lose a young child, and especially in the circumstances like that, taken by a crocodile," he told reporters.

Crocodiles involved in attacks on humans in Australia are usually captured and killed. Mr Potter said wildlife officers have been authorised to "remove" the crocodile from the area once it is located and reiterated the government's safety message.

"We live in a place where crocodiles occupy our water places... it's just a reminder to stay out of the water as best we can."

Found all around the northern edges of Australia - from Broome in Western Australia to Gladstone in Queensland - saltwater crocodiles were hunted to near extinction but numbers have bounced back since the practice was banned in the 1970s.

There have been at least two other crocodile attacks in the NT in the past year - a nine-year-old boy who was injured in January while swimming in Kakadu National Park, and a farmer who escaped a beast's jaws by biting it back in October - but there has not been a fatal attack there since 2018.

Queensland, however, has had a series of deadly attacks in recent years, including a 16-year-old boy who was killed in the Torres Strait in April.