Iranian President Mahmoud Ahmadinejad on Sunday claimed that notorious terrorist Osama bin Laden was a prisoner in U.S. custody for "sometime" before he was killed by American forces in a daring raid in Pakistan early this month.

Speaking on Iranian state television, Ahmadinejad said, "I have exact information that bin Laden was held by the American military for sometime... until the day they killed him he was a prisoner held by them. Please pay attention. This is important. He was held by them for sometime. They made him sick and while he was sick they killed him."

The Iranian leader accused U.S. president of using the death of the Al Qaeda leader for his "political gain."

"What the US president has done is for domestic political gain. In other words, they killed him for Mr Obama's election and now they are seeking to replace him with someone else," Ahmadinejad said without giving more details.

U.S. Navy SEALs commandos killed bin Laden in a daring raid on a heavily fortified compound near Pakistan's capital Islamabad on May 2.

Two days before the announcement of bin Laden's death, Iranian Defence Minister Ahmad Vahidi also raised some "suspicion" over the death of the world's number one terrorist.

Vahidi declared, "The Americans said they threw his body in the sea. Why did they not allowed an independent expert to examine the body to say if it was bin Laden or not?"

Iran, which is dominated by Shiite Muslims, have always Al-Qaeda as a Sunni ultra-radical and anti-Shiite and is a threat to its security.

But Iran is also critical of the U.S. presence in some Muslim countries, including Iraq and Afghanistan.