DRIVERS will face fines of 200 yuan (US$30) and six demerit points if they stop on Shanghai's Lupu Bridge to take photos of the Expo site, police warned today.

Shanghai traffic police said they had enforced a ban on illegal parking on the bridge since yesterday and beefed up patrols during World Expo to maintain traffic flow.

The number of the drivers punished so far was not revealed.

Police said many cars drove too slow or even parked near the Expo site to take pictures, especially at night when the park is illuminated.

"When one car stops, the one behind tries to overtake which blocks traffic in both lanes," said traffic police spokesperson Yu Dalei. "This can cause a chain reaction."

Yu said patrol teams will be on the bridge as soon as a traffic jam is reported. "Our job is to keep the traffic flowing smoothly and monitor the bridge."

Motorists with 12 points deducted in a year must undergo a seven-day training course on traffic rules before being allowed to drive again.