TEHRAN -- An explosion in a southern city some 110 miles from a nuclear facility sparked fears yesterday of a missile attack, and Iranian authorities gave conflicting explanations for the blast, including friendly fire in a military area and construction work.
The explosion occurred hours after the country's intelligence chief confirmed US drones have been flying over Iran for months to spy on nuclear and military facilities.
US and Israeli officials denied involvement in the blast, but the explosion spiked oil prices and showed how jittery the world is that growing international pressure would lead to an attack on Iran.
The explosion near the southwestern port city of Deylam, about 110 miles from the Bushehr nuclear facility, was reported by Iranian state television, which said it may have been caused by a fuel tank dropped from an Iranian plane.
A government spokesman said the blast may have been caused by friendly fire.
Later, a top security official said the blast was part of construction work on a dam. The official, Ali Agha Mohammadi of the Supreme National Security Council, said Iran's enemies were not in a position to attack Iran.
"Such reports are mostly a psychological war," he said.
The United States alleges that Iran has a secret program to make nuclear weapons. Iran insists its nuclear activities are for energy purposes.
The report of the explosion spread quickly, with some Iranians calling friends to tell them there had been an attack.
Reza Moghaddam, an engineer in the central city of Isfahan, called a friend in Tehran about rumors that the United States and Israel were attacking the Bushehr plant.
Israel has warned that it may consider a preemptive strike against Iranian nuclear installations similar to its 1981 bombing of an unfinished Iraqi nuclear reactor near Baghdad.
Secretary of State Condoleezza Rice has said a military strike against Iran was "not on the agenda at this point," but President Bush has said his administration wouldn't take any option off the table.
Interior Ministry spokesman Jahanbakhsh Khanjani, however, dismissed rumors of a hostile attack and said Iranian military aircraft routinely fly in the area.
"There is a big possibility that it was a friendly fire by mistake," he told reporters. "Several such mistaken friendly-fire incidents have been reported there in recent days."
A senior army official, speaking on the condition of anonymity, denied there had been any antiaircraft fire and said there were no military exercises in the area at the time. The official also said the explosion did not stem from a hostile attack.
"It's not very unusual that planes drop their additional fuel tank while flying, but the general public assume it's a bomb or missile attack. The army is investigating the incident," he said.
White House press secretary Scott McClellan said there was no US involvement, and CIA Director Porter Goss said he knew nothing about it.
Earlier yesterday, Iran's intelligence minister, Ali Yunesi, publicly confirmed for the first time that the United States has been flying surveillance drones in Iran's airspace to spy on its nuclear and military facilities.
"These activities won't reveal anything to them," Yunesi said of the Americans. "Our nuclear activities are open and very transparent. Our military activities are all legal."
Foreign Minister Silvan Shalom of Israel told reporters in London yesterday that Iran will have the knowledge to build nuclear weapons within six months.
Germany, Britain, and France are leading European diplomatic efforts to persuade Iran to abandon permanently its uranium-enrichment program, which the United States fears could be used to make nuclear weapons.
Foreign Minister Kamal Kharrazi urged the European Union on Tuesday to put more effort into negotiations. Iran has warned that it will resume all the nuclear activities it has suspended if no progress in the talks is seen by mid-March.