But he stressed: there are further differences.

In a side agreement, Iran released five Americans held captive, and President Obama agreed to grant clemency to seven Iranians held in the US.

"The US sanctions against Iran's ballistic missile programme... have no legal or moral legitimacy", he said.

Obama said the process of securing deal strengthened what was basically a non-existent relationship between America and Iran - even allowing a pathway to work with the Iranian government to release 10 sailors who drifted into Iranian waters last week.

The United States announced new penalties Sunday related to Iran's ballistic missile program after the lifting of punishing measures aimed at its atomic activities.

Five Iranian individuals and a number of companies based in China and the United Arab Emirates were added to the US blacklist as part of the new sanctions, according to the US Treasury. Iran also promised to cooperate with the U.S.to locate Robert Levinson, the ex-CIA contractor who disappeared in Iran in 2007, reports CBS News.

He went on to say all of the U.S. claims against Iran at the tribunal had always been settled and had netted American companies and individuals $2.5 billion. "And we are going to remain vigilant about it". The sanctions are not comparable to the economy-wide sanctions just lifted as a result of Iran's nuclear agreement with the USA and European powers.

Those sanctions came in response to Iranian ballistic-missile tests in October and November that United Nations experts determined were in violation of a 2010 UN Security Council resolution banning Iran from launches capable of delivering nuclear weapons.

US President Barack Obama said on Sunday: "We have now closed off every single path Iran had to building a bomb".

In addition, the United States and Iran have also resolved a financial dispute that dated back more than three decades.

Mr Amano met the head of Iran's Atomic Energy Organisation, Ali Akbar Salehi, and was to hold talks with President Hassan Rouhani to discuss monitoring and verifying Iran's commitments under the agreement.

"A disturbing pattern is emerging where the Obama administration is willing to negotiate the release of spies, terrorists and now criminals", Rep. Ed Royce, R-Calif., chairman of the House Foreign Affairs Committee, said Sunday in a statement.

In 1979, Iran-U.S. diplomatic ties were severed after an Iranian revolution and ties were cut completely one year later when a group of Iranian students seized the U.S. embassy in Tehran and took 52 Americans hostage, according to the website of the U.S. State Department.

Talking to the people of Iran, Obama said, "For decades your government's threats and actions to destabilise the region has isolated Iran from much of the world".