(A passenger swipes his smart phone at a subway station in Beijing. Photo/Xinhua)

Beijing's subway riders can now board trains simply by swiping their mobile phone.

Starting Sept 20, passengers taking the Airport Express can board the train by scanning the QR code after downloading an app, said the operator of the city’s metro system.

The move is the latest step taken by the operator to make mobile payments easier.

From Aug 20, passengers using Android-only phone with near-field communication, or NFC, function could swipe their phone to board a train in more than 270 stations of the metro system.

The new method, which has now been extended to all smartphone users, is expected to be adopted by the whole subway system by the first quarter of next year.