Police and rangers are searching for a boy believed to have been taken by a crocodile from a swimming hole at Kakadu National Park.

A crocodile is believed to have taken a 12-year-old boy missing from a Northern Territory billabong.

Another boy, also 12, swimming in the billabong was bitten by a crocodile, police say.

Police and Park Rangers are conducting a search and rescue mission by land and boat after being alerted to the incident at Kakadu National Park on Sunday afternoon.

Acting Commander Michael White said police believed the missing boy was taken by a crocodile as he and a number of other young boys were swimming in the billabong.

“One other boy, also aged 12, was bitten on the arm by the crocodile and has received medical treatment from attending St John Ambulance members,” Mr White said.