Australian rare earths miner Lynas Corp has scheduled for December the start-up of its processing plant in Kuantan, Malaysia, executive chairman Nicholas Curtis said at the annual general meeting in Sydney on Tuesday.

Shares of the mining firm immediately shot up to as much as 8.7 per cent to 69 cents per share upon the pronouncement.

"By the second half of calendar 2013, we expect to be moving towards full production capacity and have a business that has the potential to deliver sustainable and predictable earnings," Mr Curtis told shareholders during the meeting.

Sales from production are expected to pour in from the first quarter of calendar year 2013, he said.

During the meeting, a number of shareholders expressed their dismay at the share price, which has sunk to two-year lows. They likewise raised their concern if the present management and board of Lynas are competent to guide the company away from the legal and political issues hounding the Malaysian processing plant.

''The facility has now been monitored, inspected. The International Atomic Energy Agency has sent in a team. Lots of people have looked at it. It's handicapped by the fact that there was an earlier plant some years ago that was poorly managed and as a result, there was concern and suspicion,'' Business Day quoted Lynas board member and nuclear physicist Ziggy Switkowski.

''This is, as best as I can tell, a first-rate plant and the suggestion that there'll be genuine radiological problems that are not being addressed is ridiculous from my point of view. Having said that, I think politics and the community action have converged to create what has been a difficult situation.''

Delayed by some seven months, the $800 million plant has been touted as the world's biggest outside China. Its' supposed start-up in May was delayed by environmental and safety disputes lodged against the miner by protesting Malaysians.