The head of the UN nuclear agency has once again confirmed Iran's compliance with the 2015 nuclear agreement between Iran and the P5+1 group of countries, warning that any collapse of the deal would be a "great loss."

Director General of the International Atomic Energy Agency (IAEA) Yukiya Amano made the remarks in a speech to a quarterly meeting of the agency's Board of Governors in Vienna on Monday.

He said the IAEA has been verifying and monitoring Iran's implementation of its nuclear-related commitments under the nuclear agreement, officially known as the Joint Comprehensive Plan of Action (JCPOA), for more than two years.

"As of today, I can state that Iran is implementing its nuclear-related commitments…If the JCPOA were to fail, it would be a great loss for nuclear verification and for multilateralism," Amano added.

Iran and the five permanent members of the United Nations Security Council – the US, France, Britain, Russia and China – plus Germany signed the nuclear agreement on July 14, 2015 and started implementing it on January 16, 2016.

Under the JCPOA, Iran undertook to put limits on its nuclear program in exchange for the removal of nuclear-related sanctions imposed against Tehran.

US President Donald Trump has repeatedly described the JCPOA, which was negotiated under his predecessor, Barack Obama, as “the worst and most one-sided transaction Washington has ever entered into,” a characterization he often used during his presidential campaign, and threatened to tear it up.

Trump has threatened to pull out of the JCPOA unless Congress and America's European allies help "fix" it with a follow-up agreement within a 120-day deadline.

Since the JCPOA Implementation Day in January 2016, the IAEA has been monitoring Iran’s compliance with its nuclear-related commitments under the nuclear deal and has consistently verified the Islamic Republic’s compliance.

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"The JCPOA represents a significant gain for verification," Amano told the closed-door meeting of 35 member states.

He noted that the IAEA has requested Iran to provide further clarifications about its plans to develop the "nuclear fuel cycle related to naval nuclear propulsion."

In a report last month, the UN nuclear agency said Iran had informed the IAEA of a decision "to construct naval nuclear propulsion in future.”

The IAEA chief further said the agency would continue to verify the non-diversion of nuclear material declared by Iran under its Safeguards Agreement.

"We have had access to all the sites and locations which we needed to visit. Evaluations regarding the absence of undeclared nuclear material and activities in Iran continue," he pointed out.

In a telephone conversation with his French counterpart Emmanuel Macron on Sunday, Iranian President Hassan Rouhani once again urged all signatories to the JCPOA to remain committed to their obligations under the deal.

He said, "Tehran will remain committed to its undertakings as long as the opposite sides implement the JCPOA."

Iranian Foreign Minister Mohammad Javad Zarif in February rejected as "improper" the conditions set by the United States for upholding the multilateral nuclear agreement, urging Washington to immediately fulfill its commitments under the deal.

Zarif said, "A party to a multilateral agreement cannot set conditions for the deal. They [the Americans] have previously set some conditions that were improper. Their new conditions are improper as well."

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