Park rangers searching for a missing man in an Australian river have been ordered to kill any large crocodile they find.

The 20-year-old man disappeared while swimming in the crocodile-infested Daly River in the Northern Territory.

His partner was watching from the riverbank and told police she saw a crocodile nearby.

Police say wildlife workers are searching the river for both the man and the crocodile.

They are targeting a .6-mile section, which has been cordoned off to the public.

If the man's disappearance turns out to be the result of crocodile attack, it will be the second fatal incident in a month in the Northern Territory.

Last month, the death of an 11-year-old girl prompted calls for a crocodile cull.

Briony Goodsell had been swimming with her sister and two friends in Lambells Lagoon, near Darwin, when she was dragged under.

There are an estimated 80,000 crocodiles in the Northern Territory.

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