AS security is broadly stepped up due to terrorism fears in advance of the G20 Summit, passengers at Shanghai's two airports will now be checked for explosive residue and have their luggage X-rayed at the entrances of terminal buildings, the Shanghai Airport Authority said yesterday.

"The anti-terrorism checks have been launched at the airports according to China's Anti-terrorism Law," the authority said, adding that the new security measures will be permanent.

Passengers will also be subjected to an explosives check that involves security staff swabbing each bag with a piece of paper that is then analyzed by a machine before they are allowed to enter the building.