Rio Tinto has been put on notice for a possible credit rating downgrade because of concerns over rising debts, reinforcing the need for the Anglo Australian mining group to cut costs and make significant asset disposals this year.

Standard Poor’s yesterday said there was a one-in-three chance Rio could lose its single-A credit rating in the next 12 to 18 months if it did not bolster its balance sheet. The warning came as Ivan Glasenberg, chief executive of Glencore, the commodities trader that is buying the miner Xstrata, said global mining companies had “really screwed up” by ploughing billions into projects that did not generate returns for shareholders.

Rio Tinto chief executive Sam Walsh has pledged to maintain the single-A credit rating. – Copyright The Financial Times Limited 2013