Iran accuses the United States of being involved in a bomb attack on a Shiite mosque in the town of Zahedan on Thursday.

Mercenaries allegedly placed the bomb at the orders of Washington.

Twenty-three people were killed in the attack and about 60 injured. The bomb went off on a holiday marking the anniversary of the death of Fatima, the daughter of the Prophet Mohammed.

Zahedan is the capital of Iran's Sistan-Baluchestan province and the city is close to the borders of both Pakistan and Afghanistan. Local Iranian police are often caught up in clashes with drugs smugglers and extremists.