China plans to get tougher on loans for iron ore imports as concerns grow that steel mills are using import loans to stay afloat in defiance of policies to reduce overcapacity in heavily polluting and lossmaking industries.

The China Banking Regulatory Commission warned banks to tighten controls over letters of credit for iron ore imports in a document that caused iron ore futures in China to drop 5 per cent on Monday. Rumours of the stricter measures, which are expected after the May 1 holiday, have been circulating in China for at least two months, after a hasty stock sale caused ore prices to tumble in late February.