Australian rare earths miner Lynas has launched legal action against the most vitriolic opponents of its proposed plant in Malaysia following fierce criticism that it is unsafe.

Lynas plans to start production soon in eastern Pahang state to process rare earths imported from Australia, effectively breaking the Chinese stranglehold on the materials.

But the plant has been hugely controversial with fears it will harm the environment by producing radioactive pollution.

Protests have been held and the Lynas website hacked, proving a headache for Malaysian Prime Minister Najib Razak's government ahead of elections expected to be held soon.

Lynas says the facility -- the Lynas Advanced Material Plant (LAMP) -- is safe and has been the target of a "baseless scare campaign".

"Lynas has commenced defamation proceedings in Malaysia against the 'Save Malaysia Stop Lynas' group and various media organisations," it said in its quarterly activities report released Monday.

"The proceedings relate to various false and misleading statements that have been published in Malaysia concerning Lynas and its business."

Executive chairman Nick Curtis told Australian media Tuesday that some recent claims had crossed the line between debate and defamation.

"What we are hoping to achieve is clarity that the debate about Lynas's plant in Malaysia must be based on fact and the real issues," he said.

China supplies about 95 percent of the world's demand for rare earths, which are used in high-tech equipment from iPods to missiles and have seen prices soar in recent years.