The lower left leg of a Shanghai mall staff was amputated after an escalator collapsed Saturday, leading to renewed concerns over escalator safety.

It was the third serious escalator accident in a week.

A shopping mall employee told the Global Times that the 35-year-old man, surnamed Zhang, was cleaning the escalator while in operation on Saturday in the Longemont shopping mall in Changning district, Shanghai.

Industry insiders said it's dangerous to clean the escalator while in operation and should be banned, news website thepaper.cn said.

The comb plate on the escalator suddenly collapsed and trapped his left shin after his mop was also dragged into the cracks.

Shanghai authorities said on Weibo Sunday that "the escalator was closed and the case is under investigation."

Last week, a woman died in Jingzhou, Central China's Hubei Province while trying to rescue her 3-year-old son after the escalator collapsed, while a 1-year-old child's arm was trapped in an escalator in Wuzhou, South China's Guangdong Province.

There were 49 escalator accidents in 2014, killing 37, an official of the General Administration of Quality Supervision, Inspection and Quarantine (GAQSIQ) said, the Xinhua News Agency reported on Wednesday.

The inspection and maintenance of China's 2.4 million escalators are mostly done by the manufacturers.

The GAQSIQ's latest report said over 110,000 of them have potential safety issues, with nearly 79,000 escalators repaired and over 5,000 no longer in use. However, more than 26,000 escalators have not yet been repaired, the report said.

The central government has ordered all provincial governments, including that of Shanghai, to inspect and make sure that escalators in every mall operate properly before August 10.

Zhang Lexiang, an official of the China Elevator Association, told the Global Times Sunday that escalator accidents are caused by poor design, the use of substandard materials, installation and maintenance. Improper use of escalators also leads to accidents.