A controversial policy to catch and kill sharks off popular west coast beaches got the green light in Australia, in a move the Humane Society Tuesday termed a "complete disgrace".

The federal government granted an exemption from environmental laws to approve Western Australia's shark mitigation plan, which is aimed at reducing the risks to water users after six fatal attacks in the past two years.

It means baited drum lines with hooks designed to capture large sharks can be set one kilometre (0.62 miles) offshore at busy Western Australian beaches from now until April 30.

The state government has said that any shark longer than three metres (10 feet) snagged by the lines and deemed to be a threat -- including great white, bull and tiger sharks -- will be humanely destroyed.

In granting the exemption, Environment Minister Greg Hunt said individuals must be responsible for their own safety while swimming, surfing and boating in the open sea.

"In this particular case, however, there has been a series of tragedies due to shark attack," he said, adding that there was evidence of a significant increase in incidents off the west coast in recent years.

Hunt said the proposal was for a brief trial period and confined to a few high-use, high-risk beaches.

"One does not have to agree with a policy to accept that a national interest exemption is warranted to protect against imminent threat to life, economic damage and public safety more generally," he said.

The Humane Society said the decision flew in the face of international obligations to protect the great white shark, Australian federal law and loud public opposition to the policy.

"The exemption of the WA shark policy is a complete disgrace," said Humane Society International's Alexia Wellbelove, adding it lacked a scientific approach.

"This exemption demonstrates the complete failure of the federal government to protect our most precious species and fulfil our international environmental obligations, for the price of a policy which we do not believe will have the desired impact of reducing risk for people, which is its stated purpose."

Local marine scientists have described Australia's west coast as the world's deadliest shark attack zone, and a tagging and tracking programme is already underway in a bid to limit fatalities.

The new crackdown was triggered by the fatal mauling of a surfer at Lefthanders Beach, in the popular Margaret River tourist region, in late November -- the sixth shark killing in Western Australia in two years.

While sharks are common in Australian waters, deadly attacks are rare, with only one of the average 15 incidents a year typically proving fatal.

Experts say attacks are increasing in line with population growth and the popularity of water sports.