TEHRAN: Iran is "ready to examine" information the United States says supports accusations Tehran plotted to kill the Saudi ambassador to Washington, Foreign Minister Ali Akbar Salehi said on Monday.

"We are ready to examine with deliberation any issue, even if it was fabricated. We have asked America to provide us with information of this scenario," Salehi was quoted as saying by the official IRNA news agency.

Iran has sent a letter to US authorities via the Swiss embassy in Tehran asking for information about an Iranian-American in US custody accused of being at the centre of the alleged plot. It also demanded consular access to the suspect.

Iranian officials and leaders have fiercely denied any involvement in the alleged plot, calling it an attempt by Washington to divert attention from domestic economic woes and foreign policy failures in the Middle East.

The denials have become louder as the United States has made moves to rally other nations to a bid to further isolate Iran, which is already subject to severe economic sanctions over its controversial nuclear programme.

Iran's supreme leader, Ayatollah Ali Khamenei, warned Sunday that "any inappropriate action -- whether political or security-related -- will meet with the Iranian people's decisive response."