POLICE plan to increase co-operation with their mainland counterparts to tackle a surge in business-related kidnappings. Senior officers say the abductions - most of which have involved Hong Kong or Taiwanese businessmen - may be linked to debt collection. This year, police have rescued nine businessmen being held for ransom in Guangdong province. Deputy Director, Crime, Assistant Commissioner Dave Hodson, said he was unsure whether there had been arrests in all cases. He said many kidnappings went unreported. 'Kidnapping is perhaps too strong a word, but certainly we are seeing a big number of unlawful detentions,' he said. 'Usually, it starts as a dispute over a business debt and it is either reported to us in Hong Kong or we are notified because there is some sort of a connection here. 'Obviously, all of these have been fairly complex matters but they are taken extremely seriously. 'The main priority in these cases is making sure the victims are released. 'I think it is fair to say it is a developing problem and quite often these things are the product of misunderstandings.' Mr Hodson said investigators often went into their counterparts' jurisdiction to assist in such inquiries. Mr Hodson said he was also concerned at the emergence of a cross-border debt-collection problem. 'There's two-way traffic in these cases,' he said, 'and it is something we are seeing more of.' Police Commissioner Eddie Hui Ki-on has revealed he will make his second tour to the mainland early next year. Mr Hui, who met the Director of the Hong Kong and Macau Affairs Office, Lu Ping, on his first visit to the mainland as the force's top officer, will meet police in Guangdong in February.