TEHRAN, Iran Iran said Thursday that a bomb, not an accident, caused last month's explosion in a mosque that killed 14 people and injured more than 200.</p><p>Immediately after the April 12 blast in the southern city of Shiraz, Iranian officials said it was caused by a homemade bomb. The following day, the government changed its account and said the explosion was an accident caused by ammunition leftover from a recent military exhibition in the mosque.</p><p>But Thursday's report by the official news agency IRNA again said the explosion was no accident - and those responsible had ties to the West.</p><p>"The group that planted the bomb had been in contact with some western countries, particularly Britain and the United States," IRNA quoted Intelligence Minister Gholam Hossein Mohseni Ejehi as saying.</p><p>Iranian security agents have detained six suspects but the main suspect was sill at large, Ejehi told reporters late Wednesday.</p><p>The ministry previously did not make any information on the case public, he said, apparently in order not to tip off the suspects.</p><p>Iranian Interior Minister Mostafa Pourmohammadi also suggested Wednesday that foreign countries were somehow involved in the explosion.</p><p>"The explosion was sabotage and a plot by enemies of the Iranian nation - monarchists who have been supported by the countries that claim to be fighting terrorism and defending human rights."</p><p>Neither official named any particular group as responsible for the attack nor said how the attackers were linked to the West. No one has claimed responsibility.</p><p>Iran has repeatedly accused the U.S. and Britain of backing militants and ethnic opposition groups to destabilize the Tehran government. Both countries have denied the accusations.</p><p>Tensions between Iran and the West have grown over U.S. allegations of Iranian involvement in attacks on American troops in Iraq and over suspicions that Tehran is trying to develop nuclear weapons.</p><p>Bombings are unusual in Shiraz, where tourists come to see the ruins of nearby Persepolis, an ancient Persian kingdom that was a center for ceremonies and worship.</p><p>The mosque is part of the Rahpouyan-e-Vesal cultural center in Shiraz, about 559 miles south of the capital, Tehran.</p><p>The blast went off as the mosque's cleric was delivering a weekly speech denouncing the Bahai faith and Wahabism - an austere brand of Sunni Islam practiced mostly in Saudi Arabia, according to local news reports. Such speeches are not unusual in Iranian mosques.</p><p>The mosque was packed with about 1,000 worshippers at the time of the explosion.