A 12-year-old missing in remote northern Australia may have been "attacked by a crocodile", police said Wednesday as search teams combed a creek for signs of the child.

The child disappeared on Tuesday evening after swimming at Mango Creek near Palumpa, a small, largely Indigenous settlement about seven hours' drive southwest of territory capital Darwin.

"Initial reports stated the child had been attacked by a crocodile," Northern Territory Police said in a statement, adding that officers were now "searching a large section of the creek via boat".

Crocodile attacks are rare but not unheard of in Australia's sparsely populated Northern Territory.

A 4.5 metre (15 foot) crocodile was shot and killed after stalking locals near Palumpa in 2013.

In 2017, a 54-year-old man was mauled in a non-fatal attack in the same area.

Earlier this year, a saltwater crocodile was shot, cooked and eaten after menacing a different Northern Territory community.