Photo/Illutration In this photo released by Xinhua News Agency, a container ship from Japan is anchored at the container dock of Shanghai’s Yangshan Port in east China on April 27. (Xinhua via AP)

BEIJING--China’s export growth tumbled in April after Shanghai and other major industrial cities were shut down to fight virus outbreaks.

Exports rose 3.7 percent over a year earlier to $273.6 billion, down sharply from March’s 15.7 percent growth, customs data showed Monday. Reflecting weak Chinese demand, imports crept up 0.7 percent to $222.5 billion, in line with the previous month’s growth below 1 percent.

The data confirmed fears that the ruling Communist Party’s “zero-COVID” strategy that shut most businesses in Shanghai and other industrial centers would depress trade and activity in autos, electronics and other industries.

Forecasters expect activity to improve this month as infections ease, but President Xi Jinping last week affirmed Beijing’s commitment to “zero-COVID,” prompting expectations it will weigh on manufacturing, retailing and trade.

Exports to the United States rose 9.5 percent to $46 billion despite lingering tariff hikes in a fight over Beijing’s technology ambitions. Imports of American goods advanced 0.9 percent to $13.8 billion.

China’s global trade surplus widened by 19.4 percent to $51.1 billion while the politically volatile surplus with the United States contracted by 65 percent to $9.8 billion.

China’s case numbers in its latest outbreaks are relatively low, but Beijing’s insistence on isolating every infected person confined most of Shanghai’s 25 million people to their homes and suspended access to Guangzhou, a manufacturing and trading center in the south, and industrial center Changchun in the northeast.

Authorities have eased controls on Shanghai and allowed millions of people out of their homes, but restrictions have increased in Beijing and some other cities.

Managers of the Port of Shanghai, the world’s busiest, say it is functioning normally, but figures they cite for its daily cargo volume are down 30 percent from normal.

Auto factories and other manufacturers that tried to keep operating by having staff live at their facilities were forced to reduce or stop production because supplies of components were disrupted.

China’s economy grew by a weak 4.8 percent over a year earlier in the quarter ending in March, up from 4 percent from the final three months of 2021. Economists warned, however, there would be more downward pressure on activity in the April-June quarter due to anti-virus controls.

Consumer demand has been depressed by an official campaign to cut debt in China’s vast real estate industry, which supports millions of jobs. That triggered an economic slowdown in the second half of 2021.