Police are hunting for a man after a woman on a bus had her leg pierced by a syringe on Lantau Island on Tuesday.

The 30-year-old passenger surnamed Man got on the upper deck of a Long Win bus on route S64X at the airport at about 8am, Wen Wei Po reported.

Man sat on the left-side seat on the fifth row but suddenly felt pain in her left thigh when she stretched her leg. She then discovered a 10-centimeter syringe was embedded in the gap between the backseat of the fourth row with the needle pointing at anyone sitting behind.

Man informed the driver once the bus arrived at the Yat Tung Estate terminus in Tung Chung. The driver reported the case to police while Man was sent to Lantau Hospital for a medical examination.

Officers from Lantau’s regional crime unit are investigating the case. After an initial investigation of surveillance camera footage on the bus, police had identified a suspect.

The case has been classified as assault occasioning actual bodily harm.

A Long Win spokeswoman said the operator had instructed staff to be thorough when they make checks on their buses, adding that passengers are advised to check their seats as well and alert the driver if they see any suspicious objects or people.

Buses on many routes run by different operators were affected by at leaser 20 incidents starting last May. The cases included needles being embedded in seats and seats being slashed. At least four passengers were injured.