The head of US forces in the Middle East has warned of the risks of mounting tensions between Washington and Iran, even as President Mahmoud Ahmadi-Nejad and the west square off for a confrontation at the United Nations this week.

In a partial interview transcript released on Sunday by al-Jazeera, the television news service based in Qatar, Admiral William Fallon, head of US Central Command, gave one of the strongest indications yet that the US military is deeply reluctant to consider military action against Tehran.