Troops have completed the last big mine-clearing operation along the Sino-Vietnamese border in Yunnan nine months ahead of schedule, the PLA Yunnan Provincial Command said. More than half a million landmines and 180,000 explosive traps had been cleared since the campaign began in November 1997, following orders from the State Council and Central Military Commission, Xinhua said. The Yunnan government expressed satisfaction over the clearance which covered 104 square km, resulting in 27km of new roads and two market fairs near the frontier. Xinhua said the operation provided an opportunity for technical exploration. Scientific research units joined the PLA clearance troops to test more than 20 new mine-sweeping devices and develop new equipment. A United Nations official, who recently inspected the mine-clearing work in Yunnan, said the PLA troops were a model for similar operations in other countries, according to Xinhua. Commissioned as a two-year project, the operation's early completion may be related to the International Horticultural Expo '99 in Kunming, the provincial capital of Yunnan, which starts on May 1 and runs until October 31. Organisers hope the six-month fair, which has already cost nearly 5.4 billion yuan (HK$5 billion), will draw more than 10 million visitors from 88 countries. More than a million landmines were left along the Vietnamese border areas in Yunnan and Guangxi after the brief war between China and Vietnam in 1979. Mine clearance began a year after the two countries normalised ties in 1991.