China’s central bank injected Rmb502bn ($74bn) into its financial system yesterday to help fortify a weakening domestic economy against the impact of an escalating trade war with the US and growing friction with Washington over its falling currency.

The injection was the most emphatic move in a series of recent indications that Beijing is moving to ease monetary policy. It follows a renewed threat by Donald Trump, the US president, late last week to impose tariffs on all of China’s $500bn in exports to the US.

Raising the risk that the US-China trade war could turn into a currency war, Mr Trump has accused Beijing of manipulating the renminbi, which on Friday reached its lowest point for a year against the US dollar and has fallen 5 per cent since the start of last month.