The director-general of the nuclear watchdog for the United Nations said oil-rich Iran is meeting its commitments to downplay weapons concerns.

Yukiya Amano, the director general of the International Atomic Energy Agency, spent the weekend in Tehran discussing the terms of the Joint Comprehensive Plan of Action, a multi-lateral agreement that commits Iran to stepping away from the ability to produce a nuclear weapon.

The deal, implemented in early 2016, means some of the nuclear-related sanctions imposed by Western powers have eased and opened the door to Iran's fossil fuels industry.

Amano was quoted by Iran's state-funded broadcaster Press TV as saying his agency was "satisfied" with Iran's commitment to the JCPOA.

"The director general reiterated that the JCPOA is a net gain from a verification point of view," the IAEA's account read. "For the future, Amano stressed the vital importance of full implementation by Iran of its nuclear-related commitments in order to make the implementation sustainable."

Iran has been opening its economic doors to potential investors after so-called Implementation Day, when the country was verified as meeting the terms of a U.N.-backed nuclear agreement, passed in January. It's the only member of the Organization of Petroleum Exporting Countries that has room for production growth under the terms of an agreement to limit output starting in January.

The OPEC agreement was followed by a unanimous vote in the U.S. Senate to extend the Iran Sanctions Act for another 10 years. The measure targets energy and other Iranian industries, though the U.S. president can ease restrictions. Many of the measures were suspended when the United Nations verified this year that Iran was complying with the terms of the multilateral agreement.

In his last press conference of the year, U.S. President Barack Obama said sanctions and diplomacy paid off for both sides.

"Through diplomacy, we've ensured that Iran cannot obtain a nuclear weapon -- without going to war with Iran," he said.

Schlumberger, an oilfield services company with offices in Houston, signed a memorandum of understanding with the National Iranian Oil Co. for work on oil fields straddling the western Iranian border with Iraq in early December.