Feb 2 - State-owned China National Nuclear Corp. (CNNC) has signed a contract with Nucleoeléctrica Argentina S.A. to build the Atucha III nuclear project using China's Hualong One technology in the South American country.

CNNC said on its WeChat account late on Tuesday that signing the engineering, procurement and construction (EPC) contract marked an important milestone in nuclear ties and would help the two nations tackle the challenges of climate change together.

Progress on the nuclear deal between the two key trading partners had stalled since it was first negotiated by the administration of former President Cristina Fernandez, a left-wing populist who left office in 2015 after striking a number of deals with China.

Another CNNC-linked firm and the firm's Argentina-based unit also signed the deal on Tuesday.

The Atucha III project in the past has been reported to be worth up to $8 billion.

Details of financing of the deal were not available.

China developed Hualong One, a third generation pressurised water nuclear reactor power plant technology, to rival the Westinghouse-developed AP1000 and Europe's Evolutionary Pressurised Reactor (EPR) technology. 

China has started operating its own Hualong One reactor in southeast province of Fujian.

The Argentina project will be the second overseas location using Hualong One technology after Pakistan.

Fernandez is currently vice president of Argentina.

(Reporting by Shivani Singh in Singapore; Editing by Simon Cameron-Moore) ((ShivaniSingh2@thomsonreuters.com; +86 10 5669 2115;))