Prime Minister Dr Mahathir Mohamad has dismissed speculation that Australia's Lynas Corp was allowed to continue operating its rare earth refinery in Malaysia to further Japanese interests.

"Nothing to do with Japan," he told reporters in Kuala Lumpur today.

The anti-Lynas lobby, including Kuantan MP Fuziah Salleh, has repeatedly alleged that Malaysia was playing a role ensuring the supply of rare earth to Japan in exchange for cheap loans.

Lynas has a loan agreement with Japan Australia Rare Earths BV (Jare), and supplies Japanese customers.