The escalator which malfunctioned on Tuesday leaving one dead and 30 injured in Beijing, has flaws in its design and manufacture, and its producer OTIS should be held accountable, local authorities said Thursday.

A wounded woman receives medical treatment at the Peking University People's Hospital after an accident happened in the Beijing Zoo Station of Subway Line 4 in downtown Beijing, capital of China, July 5, 2011.

The accident happened Tuesday morning when a rising escalator, type OTIS 513 MPE, suddenly changed its direction at the A exit of the Zoo Station on Line 4 subway.

An initial investigation shows that the accident was caused by flaws in OTIS's design and manufacture. It also had something to do with the fact that the producer's maintenance was not thorough enough, said Zhang Juming, deputy chief of the municipal Quality and Technical Supervision Bureau.

The accident happened when a component malfunction led to the sudden loosening of the escalator's drive chain, according to a statement released by the municipal Quality and Technical Supervision Bureau Wednesday.

The escalator, produced by the world's largest escalator producer OTIS, was still in the guarantee period and the manufacturer just completed a routine check on June 22.

The escalator's protection mechanism that was supposed to prevent such a sudden backward movement did not work, said a spokesman of Beijing Municipal Commission of Transport on Wednesday.

The General Administration of Quality Supervision, Inspection and Quarantine has asked all the users of OTIS 513 MPE escalators in China to suspend the escalator's operation and have the producer to check them before they can be reused, Zhang said.

The 25 people who suffered slight injuries have been discharged, and the other five people are recovering, said Li Xiaosong, deputy chief of Beijing Municipal Commission of Transport.

A similar accident happened in Shenzhen Municipality in December 2010 when an OTIS 513 MPE suddenly moved backward and injured 25 people.