Police posing as hikers arrest mainland suspects in Pokfulam operation Three mainlanders thought to have been behind at least three high-profile robberies in country parks were arrested by police last night. The arrests came after a lengthy undercover operation by officers who posed as hikers and hid in the undergrowth in an attempt to snare culprits. Detectives believe the three men - who arrived from the mainland yesterday morning - are linked with at least three cases in which victims were tied to trees and ordered to reveal the PINs of their bank cards. The three incidents took place in country parks on Hong Kong Island in February, May and November last year. The arrests were made in Pokfulam Country Park at about 5pm after the three were spotted by a team of plain-clothes officers posing as hikers. 'They appeared to be nervous and they tried to evade being sighted by our officers in the country park,' said Chief Inspector Lau Tat-keung, of the Hong Kong Island regional crime unit. 'They fled in different directions when our officers approached them but were eventually stopped and subdued. A knife was found on one of them.' He said their descriptions matched those of men wanted in connection with country park robberies that had been carried out in the city. The three men, holders of multiple-entry permits, are understood to have visited Hong Kong on several occasions over the past two years. Last night they were being held for questioning in the headquarters of the Hong Kong Island regional crime unit in Western. No charges had been laid. The latest case happened on November 15 when a hiker and his girlfriend were pushed down a slope by three men and left tied to a tree for seven hours. The attackers stole $500 in cash and a mobile phone, and withdrew about $8,000 from the victims' bank accounts at an automatic teller machine. It is understood that the woman was indecently assaulted. On May 6, hiker Leung Wai-ho, 41, was tied to a tree for 17 hours after being robbed by three men in Pokfulam Country Park. Police said $65,000 was withdrawn from his bank accounts. And on February 29, a pair was tied to trees for about 12 hours in Tai Tam Country Park after being robbed by four men. Their plight came to light when the mother of the man being held called his mobile phone. The robber who had stolen the phone then told her what had happened to her son. Last year there were at least 19 robberies in country parks. In response to the crimes, police unveiled in May a pilot safety scheme under which 30 signposts showing a grid reference and emergency telephone number would be erected in certain parks to help distressed hikers.