China will not tolerate "unwanted accusations" about its investments in the UK after the delay of the Hinkley nuclear power project, the country's state-run news agency has said.
Xinhua said it could not understand the "suspicious approach that comes from nowhere to Chinese investment".
It follows reports suggesting the UK PM has national security concerns about China's role in the project.
Officially the Chinese government said it hoped for a speedy resolution.
French company EDF, which is financing most of the £18bn project, approved its investment last week - but in a surprise move the UK government then said it wanted until early autumn to review the scheme.
China is expected to fund one third of the project.
Hinkley Point: What is it and why is it important?
On Saturday, former business secretary Sir Vince Cable said then home secretary Theresa May had been unhappy with what she saw as the government's "gung-ho" approach to doing deals with Beijing when they were in the coalition cabinet together.
Nick Timothy, Mrs May's chief of staff and a long-time adviser, has also previously expressed criticisms of the Hinkley deal.
Writing on the Conservativehome website, he said MI5 believes that Chinese intelligence services "continue to work against UK interests at home and abroad".
'Horns of a dilemma'
Xinhua said the delay "not only draws queries from the international community about its openness towards foreign investment, but also adds uncertainties to the 'Golden Era' of China-UK ties".
It went on: "Giving green light to a 24-billion-U.S.-dollar project can never be an easy decision, and 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."
The news agency said China could "wait for a rational British government to make responsible decisions, but can not tolerate any unwanted accusation against its sincere and benign willingness for win-win cooperation".
Carrie Gracie, the BBC's China editor, said the Chinese government "is on the horns of a dilemma".
"It is frustrated by the uncertainty over its future in the UK's nuclear energy industry and it is angered by suggestions that the reason for the delay may be the prime minister's reported concerns about the national security implications of a Chinese role in critical infrastructure," she said.
"But Beijing does not want to feed any such fears by overreacting. Its official statement on Hinkley Point delay was bland... but it masks a very real dismay in Beijing that the so called golden era it cultivated with the previous British government might now be at an end."
Prime Minister Theresa May's official spokeswoman said: "Of course with the role that China has to play on world affairs, on the global economy, on a whole range of international issues, we are going to continue to seek a strong relationship with China."