MELBOURNE (Reuters) -Australia is considering setting a price floor to support critical minerals projects, including rare earths, Resources Minister Madeleine King said, in comments that led to a jump in share prices for Australian-listed rare earths miners.

Australia has been positioning itself as an alternative source of critical minerals to dominant producer China for use in sectors such as the automotive industry and defence.

But prices for some metals like rare earths have been too low to fund processing capacity in Western nations, meaning that China has remained the world's dominant supplier.

"Pricing certainty means companies and investors are less exposed to volatile markets and prices, which are opaque and prone to manipulation," King said in a statement first reported by the Australian newspaper on Monday evening.

Australia's policy of building a strategic reserve aims to provide price certainty for emerging critical minerals projects such as heavy rare earths, she said.

"Mechanisms for an appropriate price floor are under active consideration," she added.

Shares in Australian producer Lynas Rare Earths rallied more than 6% while shares in Iluka Resources and Arafura Rare Earths were both up more than 8% on Tuesday.

U.S. rare earths producer MP Materials last month unveiled a multibillion-dollar deal with the U.S. government to boost output of rare earth magnets and help loosen China's grip on the materials used to build weapons, electric vehicles and many electronics.

That pricing deal, which offered a minimum price floor that a buyer would pay, was set to have global implications, analysts said at the time. The move was positive for producers, but could increase costs for consumers such as automakers and in turn for their customers, analysts said.