The mainland may face a 10 million to 15 million tonne bauxite shortage if Indonesia's ban on ore exports last into next year, according to Andrew Wood, group executive of strategy and development at Melbourne-based miner, refiner and smelter Alumina.

Indonesia banned exports of bauxite ore - which is used to make alumina, which is processed into aluminium - in January, seeking to spur investment in processing.

R. Sukhyar, the country's director-general of minerals and coal, said yesterday the curb would be kept in place.

Indonesia accounted for about 18 per cent of global bauxite production last year and was the largest supplier to China, according to Citigroup.

"The Indonesian ban, and the extent it holds, is obviously a key uncertainty for Chinese refiners," Wood said at a conference in Singapore.

While there were a number of potential outcomes, all reasonable scenarios were likely to increase bauxite and alumina costs, he said.

Alumina is a partner with New York-based Alcoa in the world's largest bauxite and alumina producer. Its largest shareholder is Citic Group, the Chinese state-owned investment company.

The global bauxite market will swing to a deficit of about 6.3 million tonnes this year from a surplus of 49.3 million tonnes last year as production tumbles, according to Citigroup.

Wood said the bauxite price into China might average US$75 to US$80 a tonne on a long-term basis. The average price of China's bauxite imports last month was US$59.67 a tonne, 16 per cent higher than the US$51.64 in January.

There was potential for the Indonesian ban to be relaxed, Wood said. The government might permit companies building alumina refineries to ship some bauxite, or might allow exports of value-added bauxite that is short of alumina.

Sudirman Said, inaugurated as Indonesia's new energy and mineral resources minister this week, said yesterday the government would do "anything to maximise value of minerals for our nation's self-interest".

It typically takes four to seven tonnes of bauxite ore to make one tonne of refined aluminium. About a third of the cost of aluminium comes from alumina, while bauxite contributes less than 10 per cent, according to Paul Gait, an analyst at Sanford C. Bernstein in London.