Iran blamed the US and Israel on Friday for a bombing in a Shi'ite mosque in southeast Iran that killed 25 people, saying the countries were trying to stoke sectarian tension with the Sunni Muslim minority.
Iran has repeatedly accused the US and other Western countries of backing militants and opposition groups in the country - charges they have denied. The blame could be intended to mask real sectarian issues between Iran's Sunnis and majority Shiite population.
Thursday's bombing took place in the remote city of Zahedan, which has witnessed attacks by an Islamic militant group called Jundallah that claims to be fighting for the rights of Sunnis and is believed to have al-Qaida links.
Zahedan, located some 1,000 miles (1,600 kilometers) southeast of Teheran near Pakistan and Afghanistan, has also seen frequent clashes between drug smugglers and Iranian police.