Chinese police have launched a fraud investigation over claims that scalpers charged Chinese students who were desperate to return home at the height of the Covid-19 outbreak up to 20 times the usual rate for plane tickets.

The market price for flights shot up as countries around the world began introducing flight restrictions.

Chinese media reported that the cost of return flights between China and the US or Europe rose from around 8,000-9,000 yuan (US$1,100-1,300) to around 20,000 to 40,000…