AN urgent investigation was demanded last night after used syringes and needles, some thought to be smeared with blood, were found washed up on a popular Hong Kong beach. More than 50 syringes were found by Friends of the Earth volunteers on an ungazetted beach at Shek O yesterday. It was one of six shores throughout the territory being scoured as part of an annual United Nations-backed worldwide beach cleaning day. Shocked environmentalists who made the grim discovery have warned bathers to take precautions. Friends of the Earth urged people on beaches to wear shoes and said children should always be accompanied by adults on the territory's polluted shores. And they demanded that warning signs be erected on beaches where syringes and medical waste had been found. United Democrats legislator the Reverend Fung Chi-wood called on the Government to take immediate action. He said: ''This is a totally unacceptable situation especially on a public beach where everyone is barefoot. ''It is very risky. People can be infected with a number of diseases because of needles.'' Friends of the Earth director, Ng Fong Siu-mei, said about a third of the syringes still had needles attached. It was thought a number were splashed with blood. Their origin was not known. A blood transfusion bag and bottles of medicine were also part of the haul. Ms Ng called on the Health Department, Urban Services Department and Environmental Protection Department to investigate. She said: ''We are extremely alarmed. ''One of the two women employed by Urban Services to clean the beach told us the number of syringes being found is increasing. ''She said she had pricked herself a couple of times but didn't realise how dangerous that was. ''We are very concerned for the safety of these people and the public.'' Mr Fung, the party's environment spokesman, said a thorough investigation should find out if all medical waste was being disposed of properly. ''I hope this did not come from a public hospital,'' he added. ''The Government is thinking of adopting special procedures for the disposal of medical waste. This should be speeded up.'' Medical waste was washed up on the main beach at Stanley last month, but that mainly included unused items still in their cellophane wrappers. A Health Department spokesman refused to comment on the latest incident. The Urban Services Department said it had not been informed. A spokesman said: ''There have been instances in the past where syringes have been found. ''Hopefully they have given what they have found to the authorities so any blood samples can be checked for AIDS or other infections.'' A spokesman for the Environmental Protection Department said: ''If syringes have been found, we find that unacceptable. ''We do not know why they were there but that is something we will be trying to find out.''