Chinese and Iranian enterprises have agreed to renovate the Arak heavy water reactor, a key part of an international deal over Iran's nuclear program, and the first commercial contracts will be signed this weekend, Foreign Ministry spokesman Lu Kang said in Beijing on Thursday.

In the redesign, the reactor will be reconfigured so it cannot yield fissile plutonium usable in a nuclear bomb.

The fate of the 40-megawatt Arak reactor was a key sticking point in nearly two years of negotiations that led to the Joint Comprehensive Plan of Action on Iranian nuclear issue, signed by Iran with China, France, Russia, Britain, the United States and Germany in 2015.

According to Lu, the six powers have set up a working group, jointly headed by China and the US, on the Arak project, a core content of the JCPOA.

"The renovation project has achieved smooth progress with the efforts of all parties," he said, adding that the contract signing will create good conditions for starting the project in a substantive way.

Lu said that China, as a firm supporter of the JCPOA, is willing to work with all parties in follow-up works according to the deal and general consensus.

'Positive energy'

The spokesman said the six countries and Iran will also hold the seventh meeting of the JCPOA joint committee on Tuesday in Vienna.

"The successful signing of the contracts between China and Iran will help to inject positive energy to the meeting given the current situation," Lu said.

"We hope all parties could appropriately handle disagreements, ensure the implementation of the nuclear deal, and make positive contributions to nuclear nonproliferation and peace and stability in the Middle East," he added.

Iran has said that the Arak plant is aimed at producing isotopes for cancer and other medical treatments, and has denied that any of its nuclear activity is geared to developing weapons.

mojingxi@chinadaily.com.cn