(FINANCIAL TIMES) - In early March, truck drivers at Suto Logistics were ferrying 1,000 tonnes of goods every day in and out of Shanghai, China's most important economic hub and the world's busiest port.

By the end of last month, five weeks after local authorities had forced factories to close and residents to isolate in their homes, just one or two trucks were being dispatched daily, according to the company. And even they were no longer delivering their usual cargo of industrial materials, but "livelihood supplies" - groceries to sustain the city's 26 million residents in their enforced isolation.