A man has died after being attacked by a shark off Australia's southwest coast, officials said, adding that patrols of the area would be increased.

The West Australian state government said the attack occurred near Cull Island, which lies about 6km off the mainland's Esperance coast.

The attack on Sunday was the first fatality in Esperance since 2017, although there have been fatal attacks elsewhere in the country since then.

Last October, a British man had his foot bitten off and another was injured when they were attacked by a shark off Australia's northeast coast.

Australian Broadcasting Corp reported that the man killed today was a diver and marine police were still searching for his body while a woman on a dive boat had been taken to hospital suffering from shock.

It was not known if the man was a local or a tourist.

A 17-year-old girl was attacked by a shark in full view of her parents near Wylie Bay in 2017. She lost her leg and was pulled from the water, but died shortly after.

In 2014, a young surfer lost parts of both arms after being attacked by a great white, also off Esperance.

Australia has one of the world's highest incidences of shark attacks, but fatalities remain rare.

There were 27 attacks but no fatalities off Australia last year, according to data from Sydney's Taronga Zoo.