Eleven Iranian Revolutionary Guards were killed yesterday when a bomb destroyed their bus in a volatile border area of Iran.

The violence threatened to exacerbate tensions with the West, already high because of the stand-off over Iran’s nuclear programme. Iranian officials have frequently blamed the United States and Britain — the “arrogant powers” — for supporting rebel groups in remote border areas in an attempt to destabilise Iran.

A semi-official Iranian news agency said the daylight attack in Zahedan, the capital of Sistan-Baluchistan province, had been claimed by Jundallah (Allah’s Brigade), an extremist Sunni rebel group that Iranian officials have previously linked to al-Qaeda.

But clerics were quick to urge Iranians, who are overwhelmingly Shias, not to blame ordinary Sunnis. Tehran is wary of anything that could ignite sectarian tension; Sunnis make up about 9 per cent of the 70 million population.

Jundallah has been blamed for a series of previous attacks in Sistan-Baluchistan, a remote area important for Iran’s national security because it borders Pakistan and Afghanistan, where the American military is the dominant power.

The area also straddles main drug routes used by traffickers ferrying heroin from Afghanistan. More than 3,000 Iranian troops have been killed since the 1979 Islamic Revolution in a determined war against well-armed drug gangs.

The official Iranian news agency quoted an unnamed official as saying evidence suggested that the bus attackers had support from the United States.

Gholam Hossein Mohseni Ejeie, Iran’s Intelligence Minister, claimed last week that Tehran had identified 100 spies working for the United States and Israel in the border areas.

The attack follows sporadic violence in Iran’s oil-rich southwestern province of Khuzestan, which has a minority Arab population, and borders southern Iraq, where British troops are based.

Explosions killed more than 20 people in Khuzestan’s capital, Ahvaz, in 2005 and early 2006. London has denied as “ludicrous” Iranian accusations that Britain has fomented instability in Khuzestan.

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