Iran, the chief regional ally of Damascus, said on Saturday there is "proof" Syrian rebels used chemical weapons in their conflict with the regime of President Bashar Assad.

"We are very concerned about information regarding the use of chemical weapons in Syria, and we strongly condemn the use of such weapons," foreign ministry spokesman Abbas Araqchi said, quoted by ISNA news agency.

The possession of a nuclear bomb would threaten Iran's security, the country's foreign minister, Mohammed Javad Zarif, said in comments reported on Friday.

"We consider the possession of nuclear arms doesn't conform with the interests of the country and threatens the security of Iran," Zarif said, adding however that Iranians "will not give up their rights."

Iran's representative to the U.N.'s International Atomic Energy Agency (IAEA), Ali Asghar Soltanieh, announced his resignation on Thursday without giving any reason, the Fars news agency reported.

"My mission is finished... and I return to Iran with satisfaction," said Soltanieh, who has held the post since 2005.

The CIA has admitted orchestrating the August 1953 coup that toppled Iran's prime minister after he tried to nationalize his country's oil wealth from Britain, accordingly to declassified documents.

The Central Intelligence Agency's role in the overthrow of Mohammad Mossadegh has long been known, with the coup haunting relations between the United States and Iran six decades later.

Iran has about 18,000 centrifuges, including 10,000 active ones, the outgoing head of the country's atomic agency said Saturday, confirming figures from the U.N. watchdog overseeing its disputed nuclear drive.

"At the beginning of the month of Mordad (from July 23) we had 17,000 first generation centrifuges, of which more than 10,000 are active and 7,000 ready to start work," said Fereydoon Abbasi Davani, quoted by ISNA news agency.

Iran's new President Hasan Rowhani called Saturday for a foreign policy free of damaging sloganeering as Foreign Minister Mohammad Javad Zarif took office.

Rowhani said the clear message from voters, who gave him a surprise election victory over five conservatives on June 14, was that they wanted a new, more rational foreign policy.

New Delhi and Tehran were Saturday working to resolve a dispute over the detention of an Indian oil tanker by Iranian naval guards for allegedly polluting sea waters in the Persian Gulf.

The Indian government-owned MT Desh Shanti ship was on its way back to India from Iraq when it was stopped Tuesday by the Iranian authorities and taken to Bandar Abbas port.

The Iranian foreign minister on Friday urged the Organization of Islamic Cooperation to intervene in member state Egypt to contain a deadly crackdown on Islamists, state television reported.

Mohammad Javad Zarif said a police crackdown on two protests camps set up by supporters of deposed Islamist president Mohamed Morsi that killed nearly 600 people was a "massacre", it said.

Iran has reduced flights of arms to Syria but Iraq cannot stop them completely and should not be treated as a "whipping boy," its foreign minister said Friday.

The United States has criticized Iraq for allowing Iran to fly weapons to Syria in support of embattled President Bashar Assad in a two-year-old civil war that has claimed more than 100,000 lives.

Iran's parliament approved on Thursday all but three of President Hasan Rowhani's 18 cabinet picks, allowing the government to start work, parliament speaker Ali Larijani said.

He said on live television the proposed ministers of education, Mohammad Ali Najafi, of science, research and technology, Jafar Mili-Monfared -- both considered close to reformists -- and Massoud Sontani-far, at sports and youth, were rejected.