Iranian President Mahmoud Ahmadinejad was unharmed by an attack with a homemade explosive device on his motorcade during a visit to the western city of Hamadan on Wednesday, a source in his office said.
The source said Ahmadinejad's convoy was targeted as he was traveling from Hamadan's airport to give a speech in a local sports arena. The president was unhurt but others had been injured in the blast. One person was arrested.
"There was an attack this morning. Nothing happened to the president's car," the source told Reuters. "Investigations continue ... to find out who was behind it."
Ahmadinejad, who has cracked down on opposition since a disputed June 2009 presidential election, appeared on live Iranian television at the sports stadium in Hamadan. He was apparently well and made no mention of any assault.
The populist, hard-line Ahmadinejad has accumulated enemies in conservative and reformist circles in the Islamic Republic as well as abroad.
Al Arabiya television said an attacker had thrown a bomb at Ahmadinejad's convoy before being detained. Dubai-based Al Arabiya cited its own sources as saying the bomb had hit a car carrying journalists and presidential staff.
There was no immediate claim of responsibility.
On Monday, during a speech to a conference of expatriate Iranians in Tehran, Ahmadinejad said he believed he was the target of an assassination plot by Israel. "The stupid Zionists have hired mercenaries to assassinate me," he said.
Ahmadinejad's government is facing economic pain as new foreign sanctions imposed over Iran's disputed nuclear energy program bite on the world's fifth biggest oil exporter.
One of Ahmadinejad's trademarks has been constant travel around his vast country to deliver provocative speeches before outwardly adoring crowds who shout "death" to Iran's foes.
The oil market initially reacted calmly to reports of the attempted attack.
"I expect that any backlash there might be from Ahmadinejad will be far more important to the oil market than the initial attack itself," said Paul Harris, head of natural resources risk management at Bank of Ireland.
"You would expect the oil market to react if there is any attempt to link the attack to the current tensions with the West and the ramping up of sanctions."
Baqer Moin, a London-based Iran expert, said Hamadan was a stable area without any notable ethnic or local tension.
"Let's wait and see who they accuse, an internal or an external enemy," Moin said.
Several armed groups opposed to the government are active in Iran, mostly fighting in the name of ethnic Kurds in the northwest, Baluch in the southeast and Arabs in the southwest.
The banned Mujahideen Khalq, listed by the United States as a terrorist group, carried out several anti-government attacks after the 1979 Islamic revolution. It was blamed for two 1981 bombings that killed dozens of senior officials in Tehran, including the president and prime minister.
Shahin Gobadi, French-based spokesman for the Mujahideen, now part of an opposition coalition known as National Council of Resistance of Iran, denied involvement.
Asked if his group was behind the attack, he said: "Absolutely not, absolutely not. It has nothing to do with us. I don't know what happened but it has nothing to do with us."
Ahmadinejad recently sought to isolate rival political factions by declaring that "the regime has only one party, which is the velayat" -- a reference to Shi'ite Islam's hidden Imam, for now represented by Supreme Leader Ayatollah Ali Khamenei.
Just as combative toward external pressure, the president derided sanctions over Iran's nuclear program as "pathetic" and vowed to pursue what Iran says is a quest for nuclear energy, not weapons as the West believes.
On Monday, Ahmadinejad called on U.S. President Barack Obama to face him in a televised one-on-one debate to see who has the best solutions for the world's problems.
Ahmadinejad, backed by Khamenei and the elite Revolutionary Guards, crushed street protests that greeted his disputed re-election in June 2009, although he has yet to silence losing reformist candidates Mirhossein Mousavi and Mehdi Karoubi.
The president, first elected in 2005, also seems bent on displacing an older layer of conservative leaders and clerics whose influence dates back to the 1979 Islamic Revolution.
Many of them resent the rising economic and political power of Ahmadinejad's allies in the Revolutionary Guards and are disconcerted by his mystical devotion to the hidden Imam.
Conservatives such as parliament speaker Ali Larijani, a fierce critic of Ahmadinejad's economic policies, have tacitly urged Khamenei, the Islamic Republic's ultimate authority, to rein in the fiery president, to little visible effect.
Reformists have blamed state "discrimination" for creating discontent that has emboldened a Sunni Muslim rebel group behind two suicide bombings that killed at least 28 people in a Shi'ite mosque in southeastern Iran last month.