The launch ceremony for the interconnected metro service among seven major cities in the YRD region is held in Wuhu, Anhui province on May 22. [Photo/zjol.com.cn] 

Passengers in Ningbo, East China's Zhejiang province can now use the city's dedicated metro app to board trains in four neighboring cities by scanning a QR code on their mobile phones, according to an announcement at the first high-level forum on the integration of the Yangtze River Delta (YRD) on May 22. 

The four cities are Hangzhou and Wenzhou in Zhejiang province, Hefei in Anhui province, and Shanghai.

According to the announcement, seven cities in the YRD region are involved in the interconnected metro service, including the five abovementioned cities as well as Nanjing and Suzhou in Jiangsu province. The move marks another step forward in the integration of the YRD, after Shanghai, Hangzhou and Ningbo achieved interconnected metro services last December.

The service is expected to cover 10 cities by the end of this year, according to relevant authorities.