Passengers were well-behaved as extra security checks began yesterday at Shanghai's two airports, Hongqiao and Pudong.

Luggage and bags were searched at entrances to the terminals, besides normal check-in procedures.

Hongqiao airport opened at 5am, half an hour earlier than usual, to avoid delays for passengers and visitors.

"Thanks to the good weather and passengers' cooperation, the airport didn't encounter any unexpected situations, and no passenger was waiting for more than 10 minutes at the first security check," said Wang Jijie, deputy manager and spokesman at Hongqiao airport.

Wang said crowds are expected tomorrow and Wednesday, and suggested passengers arrive at the airport at 6am if their flights are due to take off during the morning peak. The airport generally handles 4,500 passengers from 8:30am to 11am.

"I didn't know Shanghai had implemented the new measures, but I only had to wait a few minutes to have my bags checked," said a tour guide with a Spanish group.

The checks are to detect any explosive, flammable, biochemical or radioactive material. Security workers rub bags with a piece of chemically impregnated paper, which is then scanned by a machine to produce a result in seconds.

If the machine sounds an alarm, luggage will be taken away for more detailed inspection.

Also yesterday, security checks were beefed up at Shanghai South Railway Station. Only passengers with tickets will be allowed to enter the concourse, said the rail authority.

Passengers were advised to arrive earlier than usual to allow time for the ticket and security checks before entering the station.

The checks have been tightened in the lead-up to the Beijing Olympic Games.