Police in China are cracking down on the gangs targeting tourists in the run-up to the Olympics after one unsuspecting visitor was charged $1,000 for a $7 ride.

It was just one of the scams carried out by a Chinese taxi gang accused of routinely ripping off foreigners as they arrived on the high-speed rail service from Pudong Airport to Shanghai's city center.

Eight members of the Shanghai-based gang have been accused of blackmailing 13 passengers and stealing over $8,000 in cash and goods.

In a city where a typical cab fare costs no more than a couple of dollars, police said drivers are suspected of charging tourists hundreds of dollars and then robbing or intimidating them when they refuse to pay.

Crimes against foreign visitors in China are extremely rare and the country's big cities remain among the safest in the world for tourists. But with the Olympic Games in Beijing opening in just five months, Chinese police have become even more sensitive to any scams aimed at the millions of visitors expected there.

Tough sentences are expected to be handed down on those involved in crimes against foreigners, and publicity like the $1,000 cab ride is something the Olympic authorities are desperate to avoid.