Hong Kong holidaymakers travelling in Guangdong have been warned to be on the alert for highway robbers during the Lunar New Year traffic rush. Mainland police armed with machine guns have been deployed along highways to prevent such crimes. Chen Wenfeng, director of the Guangdong Public Security Bureau's traffic unit, said: 'The robbers usually pose as passengers to get on a bus. Then on the way they use guns and knives to threaten the driver and passengers.' Traffic volume on the mainland is reaching peak levels in the run-up to the Lunar New Year. Mr Chen advised Hong Kong holidaymakers to travel with reputable bus companies. About 160,000 people entered Shenzhen through the Lowu border checkpoints yesterday, while about 100,000 mainland tourists entered Hong Kong, said immigration officer Wong Yung Siu-yau. The Immigration Department deployed 42 extra staff members at Lowu and another 38 at other checkpoints. 'We have opened all of our 76 departure counters [at Lowu],' she said. The Tourism Board deployed 27 staff at the Lowu and China-Hong Kong Ferry Terminal checkpoints to hand out information leaflets to mainland tourists. A complaints hotline manned by Putonghua speakers will operate until February 20 to assist visitors. A Tourism Board spokesman said police, transport, immigration and tourism officials would stay in contact to tackle problems. An estimated 415,000 tourists are expected to visit Hong Kong this month, up 50 per cent on February last year.