The third-generation reactor, located in Sanmen in Zhejiang province, was originally expected to make its debut in 2014.
Officials with U.S.-based Westinghouse had expected fuel loading to start last year, and it would have been followed by around six months of performance tests before the reactor could go into full operation in 2018.
But fuel loading has now been suspended as China tries to ensure the project meets the highest possible safety standards, the China Daily said, citing a spokesman with the China National Nuclear Corporation (CNNC).
Westinghouse was not immediately available for comment when contacted by Reuters on February 13.
Westinghouse, owned by Japan's Toshiba, signed an agreement in 2007 to build four AP1000 reactor units at two sites in China, hoping the projects would serve as a shop window for the firm.
But the company filed for bankruptcy last March, hit by billions of dollars of cost overruns at four nuclear reactors under construction in the United States.
China was originally seen as the lifeline for the global nuclear sector, with the country keen to approve dozens of new reactor projects to ease its dependence on polluting coal-fired electricity.
China is currently targeting total installed nuclear capacity of 58 gigawatts by the end of 2020, up from 35.8 gigawatts by the end of last year. It also said it would aim to have another 30 gigawatts under construction by the end of the decade.
But the pace of planned nuclear construction in the country was scaled back in 2011 in the wake of the Fukushima disaster in Japan.
Delays to the Sanmen and Haiyang AP1000 projects, as well as the French-designed European Pressurised Reactor units at Taishan in Guangdong province, have held back the sector, and no new nuclear project has been approved in China in two years.
China's nuclear firms are currently building their own homegrown third-generation reactor design known as the Hualong One.
(Writing by William Gao Editing by Jessie Jia)
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