British Prime Minister Theresa May has written to China's president and premier seeking to enhance trade and cooperation, amid a dispute over London delaying a $24 billion nuclear project due to security concerns over Chinese financing, Reuters said.

China has cautioned Britain against closing the door to Chinese money, warning relations are at a crucial juncture after May last month delayed signing off on the Hinkley Point nuclear project in Somerset, England.

In a statement late on Monday, August 15, China's foreign ministry cited a British envoy as telling Foreign Minister Wang Yi that Britain attached great importance to Sino-British cooperation.

Alok Sharma, Parliamentary Under Secretary of State at the Foreign and Commonwealth Office, told Wang that May had written to President Xi Jinping and Premier Li Keqiang saying she looked forward to attending next month's G20 summit in China.

Britain "looks forward to strengthening cooperation with China on trade and business and on global issues", China's foreign ministry said, citing the letter.

Wang told Sharma that China believes Britain will continue to have an open policy towards China, the ministry added.

Sharma tweeted that he had a "great" first meeting with Wang. "A warm welcome and forward looking approach."

May's predecessor, David Cameron, said the Hinkley Point project was a sign of Britain's openness to foreign investment, but May is concerned about the security implications of the planned Chinese investment and has called for a review, according to a former colleague.

China has called for the project to proceed. The plan would see France's EDF build two reactors, with partial financial backing from the Chinese state-owned company China General Nuclear Power Corp.

Britain and France's EDF first reached a broad commercial agreement on the Hinckley Point project in 2013. China got involved two years later when Downing Street laid on a state visit for President Xi Jinping, designed to cement a "Golden Era" of relations between the two countries.

China General Nuclear Power, which would hold a stake of about a third in the project, has said it respected the decision of the new British government to take the time needed to familiarise itself with the programme.