AS 300,000 people prepare to descend on Tsing Yi Island and the Castle Peak coastline for fireworks marking the completion of the Lantau link tonight, a security cordon is being drawn around the opening ceremony. With the approach of the British general election, top-level security is being applied to former Conservative prime minister Lady Thatcher, who will cut the ribbon on the suspension bridge. 'It is unusual. Police have put in extra manpower to upgrade security,' a security source said. 'Lady Thatcher has to go back to England before the elections on May 1; she is among the top 10 targets on the IRA's list.' Kwai Tsing district police chiefs, including district commander Harry Aitken are understood to have inspected the island yesterday, checking traffic arrangements. Lady Thatcher's arrival and departure details, and her seating arrangements, are being kept secret. The 20-minute, $5 million fireworks display will start at 8 pm and is expected to draw about 300,000 spectators on Tuen Mun and Castle Peak roads, which will be closed to traffic during the event. But Tsing Yi residents yesterday warned spectators against viewing the show from the island. Tsing Yi Action Group chairman Yiu Cheuk-wah pointed out the island housed three oil depots and had been rated 'high risk' in a Government study. 'The spectators' safety is at stake because there is no contingency plan to evacuate them in the event of accidents,' Mr Yiu said. Some 2,000 cars had flooded on to the island during the last fireworks display at the Gold Coast, he said. 'More people are expected to use the island as a viewing place this time and paralyse the island when they try to disperse.'