As China and the U.S. battle over tariffs, locked in a tussle that could result in a deal or a trade war between the world's two largest economies, staying away from China's stock market is becoming the default option for foreign investors.

But Mr Trump’s most incendiary claims are reserved for China. The Communist Party, he says, “has subsidised and otherwise incentivised” Chinese firms to “export fentanyl and related precursor chemicals that are used to produce synthetic opioids sold illicitly in the United States”.

China's stocks and currency came under pressure as markets returning from a week-long break were greeted by a new trade dispute with the United States and ructions in the global artificial intelligence sector.