Three killings of Macau civil servants in as many weeks have raised fears over security for Portuguese Prime Minister Antonio Guterres, who is due to begin a three-day visit to the enclave tomorrow. However, police sources said yesterday that tight security would be in force for the premier's first official visit to Macau. Outspoken democratic legislator Antonio Ng Kuok-cheong had warned that organised crime elements could be planning a high-profile attack. He claimed top gangland figures wanted 'concessions' from Macau authorities and that yesterday's murder of government chauffeur Wong Kam-seng was another example of the pressure they felt able to exert. 'I fear for the Prime Minister's safety,' he said. 'I think it is obvious that crime bosses think the police have no power to control the situation. So they may well try to kill some more officers,' said Mr Ng. 'They are saying to the Government, 'if you don't want to lose face again, you must promise some concessions for our organisations'. 'It is a clear message. This is why the Government must have some serious security arrangements in place for the visit.' The chauffeur's murder comes less than three weeks after the daylight killings of senior gambling inspector Francisco Amaral and marine police officer Chu Ion-kao.