"This morning a hand grenade exploded next to a vehicle carrying reporters accompanying the president" in the city of Hamedan, reported Khabaronline, a news website close to parliament speaker Ali Larijani.

"Ahmadinejads car was 100 metres (yards) away and he was not hurt," it said, adding that the alleged attacker was detained.

Irans Mehr news agency quoting witnesses said a "hand-made noise bomb exploded a far distance from the presidents car" in Hamedan.

"Nobody was hurt and several people have been arrested," the agency said.

Ahmadinejad later delivered a live televised speech to locals gathered in a stadium in Hamedan but made no reference to the alleged incident.

An official in Ahmadinejads media office told AFP that the explosion was from a "firecracker."

"It was a firecracker, and a statement will be released soon," the official said.

Irans ISNA and ILNA news agencies also said the blast was caused by a "firecracker" while Fars news agency said a "hand-made grenade" had been thrown at the motorcade."After the presidents motorcade passed someone threw a hand-made grenade at the vehicles behind it," Fars said.

The agency used the term "narenjak" for the explosive, which means a grenade but applies to home-made noisy crackers, the size of a tennis ball, that Iranians set off at festive events such as the New Year fire festival.

"Security agents arrested the person who threw it," Fars said, adding that the incident had "irritated" the well-wishers, but did not say if anyone had been hurt.

The incident came only two days after Ahmadinejad repeated his claim that Irans archfoe Israel wants him dead.

"Stupid Zionists have hired mercenaries to assassinate me," Ahmadinejad said in a televised speech to expatriate Iranians on Monday.

Irans foreign ministry spokesman on Tuesday also insisted that the hardliner is on Israels hit list.

"It is quite evident that the Zionist forces are under state orders to assassinate different figures in the Islamic world," Ramin Mehmanparast told reporters.

"They may dare in their mind to assassinate Islamic world figures as soon as they have access to them and one of the greatest enemies of this regime is Dr. Ahmadinejad."

The animosity between Iran and Israel has steadily worsened under the presidency of Ahmadinejad who has infuriated the world powers by dismissing the Holocaust as a "myth."

Israel too has never ruled out a military strike against Iran to stop its nuclear programme. On its part, Iran does not acknowledge Israel.