Rio Tinto is considering selling parts of its aluminium business to bolster its financial performance, the company says.

The world's second largest mining company took over Alcan in 2007.

It plans to sell six units in Australia and New Zealand and seven plants in France, Germany, the United States and the United Kingdom at an unspecified "appropriate point in the future", the company said in a statement.

The assets are "no longer aligned" with company strategy, chief executive officer Tom Albanese said.

"The strength of our balance sheet means that we can choose the most opportune method and timing to divest these assets, which may not occur until the economic climate improves," Mr Albanese said.

The Australian and New Zealand assets in question will be transferred to a new division to be called Pacific Aluminium before being sold.

The Boyne aluminium smelters in Gladstone in central Queensland and the Bell Bay smelter in northern Tasmania are among the facilities to be offloaded.

Rio Tinto Alcan chief executive Jacynthe Cote says the sell-off follows a strategic review.

"Thirteen plants will be divested at an appropriate point in the future and some of there will be managed separately in the meantime," she said.

"The move will allow Rio Tinto Alcan to concentrate on its strategy to develop and operate top tier assets and further improve the product group's financial performance."

Ms Cote says there are several factors behind its decision, including the cost of electricity.

"I think Rio Tinto expressed its views publicly on the climate change regulation. but today's announcement is way beyond that," she said.

"Following our strategic review we've identified these 13 plants while being sound businesses again, well managed, not being aligned any longer with our core strategy."

Financial analyst Dale Long told ABC Local Radio the Alcan acquisition had hit the company's bottom line.

"They bought the Alcan business, which has been let's say not one of their better purchases in times gone by, and this is a direct result of that," Mr Long said.

"They want to divest that because it's been hurting their balance sheet over the last few years."

Rio Tinto's share price was up 30 cents to $69.93 at 11:20am (AEDT)

Gladstone Deputy Mayor Matt Burnett says he is very surprised that Rio Tinto is planning to sell off its Boyne Aluminium smelters and the central Queensland city's power station.

Councillor Burnett says he thought the company would want to retain ownership of the Boyne smelters.

"They've got their shares in the Queensland Alumina Limited and Rio Tinto at Yarwun and also NRG, so it makes sense of them to have the final end of the product for the bauxite coming in to becoming alumina," he said.

"The power that's required to make aluminium at the end with their share with NRG, you would think that they'd want to keep their ownership of Boyne Smelters, but I guess Rio makes decisions on a global scale."