VIENNA - The International Atomic Energy Agency's (IAEA) 63rd General Conference opened here on Monday amid heightened tensions over the Iran nuclear deal.

Many of the IAEA's 171 member states are represented at the meeting from Monday to Friday. The application of the IAEA's safeguards in the Middle East and in the Democratic People's Republic of Korea, as well as issues related to radiation safety and ways of strengthening the agency's technical cooperation activities are on the agenda.

Discussing the crisis over Iran nuclear deal, IAEA Acting Director General Cornel Feruta told the conference: "A week ago I visited Tehran for talks with senior Iranian officials ... I continue to emphasize the importance of full and timely cooperation by Iran in the implementation of its Safeguards Agreement and additional protocol."

"The agency continues to verify the non-diversion of nuclear material declared by Iran under its Safeguards Agreement," said the acting IAEA chief, noting that "Evaluations regarding the absence of the undeclared nuclear material and activities in Iran continue."

Ali Akbar Salehi, head of the Atomic Energy Organization of Iran (AEOI), condemned the "economic terrorism" pursued by the US administration and called on the international community to assume joint responsibility for saving the Joint Comprehensive Plan of Action (JCPOA).

"The violation of the United Nations Security Council (UNSC) resolution (2231) and the imposition of unilateral unlawful sanctions, as well as the application of extra-territorial national laws to other countries by the United States, certainly endangers international peace and security," he said.

"If the international community fails to save the JCPOA promptly, multilateralism will lose its effectiveness, and any further peaceful resolution of global conflicts will be challenged, which will subsequently serve the malign interests of warmongers," he said.

While Iran said that the steps to downgrade its nuclear commitments aim to "provide a new window for diplomacy to preserve the deal," the US called it a nuclear blackmail.

"Iran continues to use its nuclear program to extort the international community and threaten regional security," according to a message from US President Donald Trump shared with the conference by US Energy Secretary Rick Perry.

The European Union (EU), on the other hand, noted Iran's "stated intentions" to remain within the JCPOA and urged the country to reverse its steps and return to full JCPOA compliance, according to Petri Peltonen, Finland's under-secretary of state at the Ministry of Economic Affairs and Employment.

"The EU deeply regrets the withdrawal of the United States from the JCPOA and the reimposed sanctions, and calls upon all countries to refrain from taking actions that impede the implementation of the JCPOA," said Peltonen.

The EU is deeply concerned that Iran has exceeded the JCPOA stockpile limit of enriched uranium, and is particularly concerned about the development reported by the IAEA regarding Iran's expansion of its centrifuge R&D activities, according to Peltonen.

He stressed that the full implementation of the nuclear deal by Iran is and remains essential.

Perry echoed US Secretary of State Mike Pompeo's accusation that Iran was responsible for launching the recent drone attacks on two Aramco oil facilities in the east of Saudi Arabia, which caused major damages and halved Saudi oil output.

Iran's Foreign Ministry on Monday rejected the US claims that Iran was behind the drone attacks, saying "such claims are baseless and are condemned."

The United Nations' atomic watchdog confirmed earlier last week that advanced centrifuges had been installed at an Iranian nuclear plant in breach of limitations set by the 2015 nuclear deal with major powers.

In reaction to the unilateral withdrawal by the US from the JCPOA and its sanctions on Tehran, and in response to Europe's "inactivity" to save Iran's interests under the deal, Iran decided in May this year to scale back its obligations under the JCPOA to build stockpiles of nuclear fuel and enrich low-grade uranium to a higher level of purity.

It also decided to start up advanced centrifuges to boost the country's stockpile of enriched uranium.