Major cities, including Beijing and Guangzhou, have strengthened safety measures after the subway tunnel collapse in Hangzhou on Saturday in which seven people died.

Authorities in Beijing, where seven urban railway lines are being built, have vowed to intensify checks on all construction sites.

They have promised to install close-circuit TV cameras, too, to monitor the sites round the clock, the Beijing Youth Daily reported. Wu Hongjian, general manager of the Beijing Railway Construction and Management Co, said cameras would be installed at all the construction sites of the seven lines under construction.