A sophisticated tent hideout used by mainland illegal immigrants - complete with a workout area, kitchen and crude plumbing - has been discovered on a hillside in Ma On Shan Country Park. Three tents made up a bedroom, kitchen and living area. A hammock made from a nylon net erected between two trees and a Chinese chess set were also found among the tents, built from bamboo poles and nylon sheets. The illegal immigrants' hideout was discovered during an air and land search involving 70 policemen, police dogs and a Government Flying Service helicopter yesterday morning. No one was found in the shelter. Police say the site is a 45-minute walk up a hill from Mui Tsz Lam Road. A rubber tube leading from a nearby stream served as a convenient water source in the shelter, officers said. The kitchen tent had food and cooking equipment such as a water pot and frying pan, according to Senior Inspector Paul Lau Fu-wah of Ma On Shan police station. 'Another tent is used as a bedroom where two mattresses are placed on top of some bamboo poles,' he said. The third tent, which was empty, was apparently used as a living room where they could take a rest, eat and chat. But no furniture was found inside. 'They could do exercises to keep fit with the weights and a horizontal bar which was built between two trees outside the tents,' Mr Lau said. 'They could also relax by sleeping in the hammock outside the tent or playing chess.' He said it was the first time that police had discovered a shelter for illegal immigrants equipped with such facilities. Each of the tents was about two metres by three metres. Officers believe that the shelter, which could house five to six people, had been in place about six months. Yesterday's search was prompted after officers arrested a mainland illegal immigrant in connection with a theft case in Ma On Shan on April 9. During the officers' inquiries, the man revealed the location of the shelter. Police said there were eight robberies in the country park last year but no cases were reported this year. The number of crime cases reported in Sha Tin and Ma On Shan involving mainland illegal immigrants dropped to one in the first quarter of this year from 14 in the same period last year.