Shares in Rio Tinto fell by nearly 10 per cent this morning after the global mining group said it would delay plans to sell $10 billion (£5.74 billion) of assets amid the ongoing financial crisis.

Rio Tinto had promised a total of $15 billion in divestments, aimed at recouping some of the $39 billion it paid for Alcan, the aluminium group, last year.

In a third-quarter trading statement the group said that its overall outlook remained positive, but that market turmoil was forcing it to reconsider the schedule for the first $10 billion of the sales.

The company said: "Acknowledging the reality of the currently challenging financial markets, the group is reviewing its timeline for the announcement of the first $10 billion of divestments, which was due to be made in 2008."

Tom Albanese, chief executive of Rio Tinto, said: "Against the backdrop of the current markets, the Group is taking the opportunity to review the near term spending timelines and project costs of its capital expenditure programme."

Rio also warned of slackening demand for commodities in China, a further cause for market concern.

Mr Albanese said: "In the near term, the Chinese economy is pausing for breath. China is not completely insulated from an OECD recession and we will see an impact on Chinese exports."

Mr Albanese said that the slowdown was confined to the near term, a combination of tighter Chinese monetary policy introduced last year to tackle inflation, and the postponement of projects during the Beijing Olympics.

However, Rio's warning is significant as is the first indication from a major supplier that the Chinese appetite for raw materials may be waning.

Quarterly global production of iron ore rose 17 per cent on the same period last year, but refined copper production fell 30 per cent. Rio said the fall was due to the impact of lower ore grades on mine production at Escondida, the giant mine in Chile which it owns with BHP Billiton.

The third quarter review from the miner made no mention of the unsolicited takeover offer from BHP Billion, whose shares decined by 10 per cent to 969p on Rio's statement.

Shares in Rio fell by 9.8 per cent to £25.48.

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