China yesterday warned the UK it had jeopardised post-Brexit relations by sailing a British warship close to islands in the South China Sea claimed by Beijing last week.

Britain has been working to boost trade with the world’s second-largest economy as Brexit looms, talking up a “golden era” in ties.

The two nations agreed last month to look at the possibility of a post-Brexit free trade deal that, if struck, would be a key achievement for Prime Minister Theresa May.

"What the British side did is wrong,” said Chinese Foreign MInistry spokeswoman Hua Chunying in a daily press briefing. “It will have a negative impact on the development of China-UK relations.”

Chinese state media specifically cautioned that a post-Brexit trade deal was at stake. “China and the UK had agreed to actively explore the possibility of discussing a free trade agreement after Brexit, but any act that harms China's core interests will only put a spanner in the works,” said an English-language editorial in state-run newspaper China Daily.

“But by trying to revive the ‘special relationship’ in this way now it is no longer the gateway to continental Europe, the UK risks losing more than it can gain,” said the editorial.