China urged the UK government to press ahead with the Hinkley Point C nuclear power plant, after it delayed making a final decision until October.
Reports suggest Prime Minister Theresa May pushed back final approval last week because of security concerns regarding the involvement of China's state nuclear company, which would own about a third of the project.
Hua Chunying, a spokesman for the Chinese foreign ministry told Reuters that Beijing had "noted" the decision.
"I would like to stress that this project was agreed upon by China, Britain and France in the spirit of mutual benefit and cooperation, and win-win cooperation, and has always had the strong support of Britain and France," she said.
Hua continued: "[China] hopes that Britain can reach a decision as soon as possible, to ensure the project's smooth implementation."
But China's state media agency launched a stinging attack on fears that China could plant "back-doors", giving it control of critical UK energy infrastructure.
Writing in an editorial, it said the move "draws queries from the international community about [the UK's] openness towards foreign investment, but also adds uncertainties to the 'Golden Era' of China-UK ties."
"China fully understands and respects British government's requirement for more time to ponder. However, what China cannot understand is the 'suspicious approach' that comes from nowhere to Chinese investment in making the postponement."
Moreover, it said alleged security fears were particularly harmful to a country "striving to pull itself out of the Brexit aftermath, openness is the key way out" and that the new government "is actually running the risk of dampening the hard-won mutual trust with China."