Beijing says Iranian and Chinese companies will sign the first commercial contracts to redesign the Arak heavy water nuclear reactor in central Iran in the weekend.

Chinese Foreign Ministry spokesman, Lu Kang, told a daily news briefing on Thursday that the accords would be inked in Vienna on Sunday, with initial agreements having already been reached in Beijing.

He further described the contracts as an important part of the 2015 Iran nuclear deal, dubbed the Joint Comprehensive Plan of Action (JCPOA).

Lu said China and the US were joint heads of the working group on the Arak project, adding that smooth progress had been made on the plan.

"The signing of this contract will create good conditions for substantively starting the redesign project,” he said.

The 40-megawatt Arak reactor is intended to produce isotopes for cancer and other medical treatments. Iran is redesigning the planned research reactor to sharply cut its potential output of plutonium.

The photo shows Iran's nuclear facility in the central city of Arak. (Photo by AP)

Iran has removed the sensitive core of the reactor and UN inspectors have visited the site to verify the move, which is crucial to the implementation of the JCPOA.

Iran and the P5+1 countries — the United States, Britain, France, China and Russia plus Germany — signed the JCPOA on July 14, 2015 and started implementing it on January 16, 2016.

Under the agreement, limits were put on Iran’s nuclear activities in exchange for, among other things, the removal of all nuclear-related bans against the Islamic Republic.

The UN Security Council later unanimously endorsed a resolution that effectively turned the JCPOA into international law.

Elsewhere in his comments, the Chinese diplomat expressed hope that all parties to the JCPOA would appropriately handle disagreements and ensure that the deal was implemented.

The administration of US President Donald Trump has adopted a hostile stance on the Islamic Republic and is currently undertaking a review of the US policy on Iran.

On Tuesday, US Secretary of State Rex Tillerson acknowledged that Iran was complying with the nuclear deal, claiming, however, that the JCPOA had merely “delayed Iran’s goal of becoming a nuclear state.”

One day later, he accused Iran of “alarming ongoing provocations” to destabilize countries in the Middle East. He also stressed that the US policy review would not only look at Tehran's compliance with the nuclear agreement, but also its behavior in the region.

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