Reuters reports that U.S. companies in China are increasingly fretful that trade tensions between the world's two biggest economies will drag out over years and nearly a third said their ability to retain staff had been affected, a survey showed.

Half of the firms said they believe soured ties will last at least three years, up sharply from 30% in 2019, according to an annual business sentiment survey conducted by the American Chamber Commerce in Shanghai and consultancy PwC China.

Of those, 27% said they believe tensions will last indefinitely, compared with just 13% last year.

"U.S.-China tension is the top concern for the American business community here," Ker Gibbs, president of the business chamber, said at an event to mark the release of the report.

"This Beijing, Washington dialogue, they need to work this out, because it's having an impact on business performance here."