A mainland tourist who claims he mistook a plainclothes policeman for a robber and was pushed to the ground during a chase through Ocean Park is suing the officer and the secretary for justice. In a High Court writ filed yesterday, Deng Ying-cheng, who is also known as Tang Ying-shing, claims the incident happened during a tour of Ocean Park on September 9, 2000. The writ says he and his tour group were walking through the park when he felt his right arm being grabbed from behind. When Mr Deng turned his head he saw Shiu Hang-yip, a policeman who was dressed casually and who did not say anything to him. He also noticed a second group member, Liu Can-sang, being subdued by another man, the writ says. 'Mr Deng was frightened, thinking that he and his fellow member were encountering robbers,' it says. 'Mr Deng struggled and wrenched himself from the clutch of Mr Shiu. Mr Deng ran away in order to avoid Mr Shiu, who was perceived by Mr Deng to be a robber.' The writ says Mr Shiu then chased the startled Mr Deng and pushed him from behind. It was in the course of losing his balance and falling that Mr Deng suffered 'serious personal injuries', the writ says. No other details were provided. Mr Deng is seeking undisclosed damages.