BEIRUT, (Reuters) – Economic or ethnic discontent may  lie behind an apparently amateurish attack on Iranian President  Mahmoud Ahmadinejad’s convoy yesterday — if such it was —  rather than any plot by militants or foreign foes to kill him.

Ahmadinejad, one of Iran’s most divisive leaders since the  1979 Islamic revolution, is defying tougher sanctions over his  country’s nuclear programme, but is under fire from reformist  and conservative critics of his foreign and economic policies.

His disputed re-election in June 2009 provoked huge street  protests that were crushed by security forces led by the elite  Revolutionary Guards.
Defeated candidates Mirhossein Mousavi and  Mehdi Karoubi always urged their supporters to avoid violence.

A source in the president’s office said Ahmadinejad survived  unhurt when a home-made explosive device was thrown at his  motorcade as it drove through the western city of Hamadan.

Some Iranian media denied there had been any attack at all,  or sharply toned down their initial accounts of the blast.

The semi-official Fars news agency, after first reporting a  man had hurled a home-made grenade, later said a firecracker had  been set off by a man who was “excited” to see the president.

There was no official word on who was behind the bang and no  claim of responsibility.

Speculation about possible culprits  ranged from foreign intelligence services to Iranian ethnic  militants and other domestic opponents of Ahmadinejad.