SHANGHAI: The United States has ordered all non-essential employees at its Shanghai consulate to leave over concerns about their safety, an embassy spokesperson said in a statement Tuesday, as the Chinese city faces a spike in Covid cases and a harsh lockdown.

The US State Department "ordered the departure due to the ongoing Covid-19 outbreak" and US diplomats have raised "concerns about the safety and welfare of U.S. citizens with People's Republic of China officials," the spokesperson said in the statement.

China has stuck to a policy of "zero Covid", aiming to eliminate infections through rigid lockdowns, mass testing and travel restrictions.

Shanghai has been placed under some of the most severe measures since the virus first emerged in Wuhan in 2019, with a strict lockdown leaving many struggling to get enough food and thousands sent to quarantine centres.

The megacity reported more than 23,000 new Covid infections on Tuesday, with most of its 25 million residents still under strict lockdown.

The US embassy said last week it would permit non-essential employees to leave its consulate in Shanghai due to the case surge, warning citizens in China they may face "arbitrary enforcement" of virus curbs.

The State Department is now ordering employees to leave as "it is best for our employees and their families to be reduced in number and our operations to be scaled down as we deal with the changing circumstances on the ground," the spokesperson said in the statement.