Amano, 62, handled nuclear proliferation issues for the Foreign Ministry for three decades. He joined the IAEA’s 35-member board of governors in September 2005 and was elected the agency’s director general in July.

Amano assumes his post two days after President Mahmoud Ahmadinejad’s Cabinet ordered Iran’s nuclear agency to begin building 10 uranium enrichment sites within two months, according to the Islamic Republic News Agency. Iran says the fuel is for civilian use while the U.S. claims it is for weapons development.

“Iran seems to be saying its last ‘goodbye’ to ElBaradei and saying ‘hello’ to Amano,” said Takehiko Yamamoto, a professor of international relations at Waseda University. “There’s a tough road ahead of Amano, with his first and major task being to beef up the agency’s inspections of Iran’s nuclear sites and shoot down the country’s ambitious nuclear armament plans.”

The IRNA report came a day after the U.N. agency censured Iran for concealing the existence of an enrichment plant built into the side of a mountain. The IAEA board demanded that Iran suspend construction of the almost-completed Fordo plant.

Iran already faces three sets of U.N. Security Council resolutions over its nuclear program. ElBaradei, a Nobel Peace Prize laureate, said Friday the agency had reached a “dead end” in its six-year investigation into whether Iran is concealing a nuclear weapons program.

Amano’s appointment comes as the IAEA tries to balance the growing demand for nuclear reactors against the spread of weapons technologies through the network of Pakistan’s Abdul Qadeer Khan.

The former head of Pakistan’s nuclear and missile programs was placed under house arrest in 2004 after confessing to running a network that sold machinery for making bomb-grade uranium to Iran, Libya and North Korea.

IAEA inspectors were kicked out of North Korea on April 16, a month before that nation tested a nuclear device. The Security Council in June imposed more sanctions against the Stalinist state, including restricting financial transactions.

Amano, who studied law at the University of Tokyo before joining the diplomatic corps in 1972, failed to win majority support in three meetings of the IAEA board. He was elected in July after an unidentified country changed its vote from no to abstain.