Britain and America are furious with Austria for exporting to Iran 800 sniper rifles that could be used against their troops in Iraq.

HS50 Steyr-Mannlicher .50 calibre rifles can pierce body armour from up to a mile, shoot down helicopters and penetrate Humvee troop carriers that have not been fully reinforced.

The weapons are highly accurate and fire a round called an armour-piercing incendiary, a bullet that the Iranians manufacture.

There are fears in the Pentagon that some will reach insurgents fighting allied forces in Iraq.

Iran's Revolutionary Guard is suspected of passing on bomb-making technology to Iraqi terrorists responsible for infra-red bombs that have killed 10 British soldiers.

A Foreign Office spokesman said there were "serious concerns" over the rifle sale and London had protested to Vienna...