A woman is feared dead after a crocodile attack in Australia's Daintree National Park.

The 46-year-old Australian was reportedly swimming with a friend on Sunday evening at Thornton Beach near Cairns in northern Queensland state.

She was in waist-deep water when she was attacked, media reports said.

The last fatal attack in the area occurred in 2009, according to the Australian Broadcasting Corp.

"We would hold grave fears for the welfare of the woman," police spokesman Russell Parker said.

"Her 47-year-old friend tried to grab her and drag her to safety and she just wasn't able to do that.

"[The friend] then ran to a nearby business and raised the alarm, and from that point police and other authorities were advised.

"They had been walking along the beach and they've decided to go for a swim just in waist-deep water at Thornton Beach and probably a very nice, clear night, but obviously may not have been aware of the dangers."

Nine News reported that witnesses heard the woman yell: "A croc's got me, a croc's got me."

A search for the missing woman resumed on Monday morning. Her friend is being treated for a graze and shock.