Mumbai: Global miner Rio Tinto posted a 55 per cent jump in first-half profit, boosted by a near doubling of iron ore prices amidst strong demand from China and other Asian countries.

Rio Tinto, which took over Canadian aluminium major Alcan last year, also raised its dividend. The company also forecast a firm outlook in the coming years.

''While the equity markets are currently focused on downside risks, we believe there are potential offsets on the upside based on continued strength in commodity demand, low inventory levels and a supply side which continues to face multiple constraints,'' chairman Paul Skinner said in a statement.

''The group continues to perform strongly, and the outlook remains positive," he said.

Rio Tinto, meanwhile, is trying to deflect a $150 billion takeover bid from bigger rival BHP Billiton saying it is too low. Australia's competition commission, too, last week said a merger of the two mining giants would have implications for iron ore prices, which are already on the boil.

Skinner reiterated the group's view that BHP's offer of 3.4 shares for each Rio Tinto share was too low. ''The group's performance in the first half, together with our growth potential, supports the boards' view that Rio Tinto presents a very strong standalone value proposition for shareholders,'' he said.

China's iron ore imports were up 20 per cent from last year, despite skyrocketing prices of the raw material.

Rio Tinto, which sold its stakes in the Cortez gold mine and Greens Creek silver, lead and zinc mine and its Kintyre uranium project, said it hopes to complete sale of assets worth $10 billion by the end of this year.

Profit after tax from Alcan is expected to rise to $1.1 billion at end-2009 from a previous $940 million.

Excluding one-time gains profit rose to $5.474 billion in January-June from $3.529 billion a year earlier.

Rio Tinto, which raised its interim dividend by 31 per cent to 68 cents a share, also raised its full-year dividend by 20 per cent each in in 2008 and 2009.