IMMIGRATION officials at Lo Wu opened five extra processing counters last night after a record number of people used the border checkpoint during the Ching Ming festival weekend. The checkpoint closed for the day at 11 pm after processing 79,619 returning travellers and 30,241 departing residents. Lo Wu is the busiest migration point and about half the territory's holiday-makers exit or enter through there. The Chief Immigration Officer at Lo Wu, Mr Paul Wai Fok-cheung, said five departure counters had been turned into arrival ones to provide a total of 44. About 40 extra counter clearance officers had been brought in for the weekend to boost numbers to 170. Saturday's processing of almost 101,797 residents departing and 37,459 arriving had set a record for Lo Wu. Another 83,740 people departed through Lo Wu on Sunday while fewer than 34,511 returned. ''Immigration officers have done as well as they can, given the increased numbers and that we have to check for illegal immigrants,'' Mr Wai said. Ching Ming is the time when Chinese express their respect to ancestors by sweeping their graves. Crowds did not appear inside the territory, since the Ching Ming Festival this year followed the weekend so people could choose any one of the three holidays to go grave-sweeping. A Kowloon-Canton Railway spokesman said their trains had carried almost 216,000 passengers to and from the border over the weekend. Police put on 26 extra officers so they could have 51 officers for the three shifts at the checkpoint. A total of about 670,000 people left Hongkong through all ports between Thursday and Sunday night, and about 405,000 returned.