A 28-year-old man was killed by a shark while he was spearfishing with his friends off the southern coast of Australia on Saturday.

According to police reports, the man went missing in the water off Goldsmith Beach, near Yorke Peninsula, west of Adelaide.

"At about midday, the man was part of a group spear-fishing at a popular area at Goldsmith Beach when witnesses report seeing a shark attack the man," police reportedly said.

According to reports, the police and emergency services crew searched the area with boats and helicopters but were unable to find any trace of the man, who was from Adelaide.

Witnesses told police the man had been thrashing about in the water after a shark, believed to be a great white, approached him.

According to reports, Sgt. Mark Stuart said: "Some of them did witness it. From what we can gather they were an experienced group of fishermen and they were on the peninsula to participate in a spearfishing competition tomorrow.”

He added, “They were diving loosely in a group, probably within a few hundred metres of each other.”

The great white shark had been in the area for about a week as it was attracted by an abundance of snapper fish.

The incident comes a week after thousands of people rallied across the country against a shark culling policy in Western Australia that is designed to prevent attacks. The policy is not in effect in South Australia.

The policy states that great white sharks, tiger sharks and bull shark that are larger than 3 meters will be caught and killed, while the smaller ones would be released. The measure was proposed last month due to the six fatal shark attacks over the past two years.

Opponents argue that there was no scientific evidence that killing the sharks would reduce the risk to swimmers.