Lawrence Summers, the president of Harvard University and former US Treasury secretary, has warned that there is a dangerous degree of complacency about global economic imbalances.

Commenting on the general lack of concern at the World Economic Forum about the soaring US trade, Mr Summers recalled the sense of calm that existed before the Mexcian crisis in 1994 and the bursting of the technology bubble in 2000. "The time of greatest serenity was also the time of greatest risk".