POLICE have launched an international hunt for two tug-of-love children after their estranged father abducted them from England and brought them to Hong Kong. The search has now widened to China where it is believed John Brook and daughters Emma, nine, and Amy Kate, six, are in hiding. Government House and Interpol yesterday confirmed they were 'aware' of the situation and vowed to do all they could to assist. But European law enforcers cannot make arrests in China, so the girls will be returned only if the mainland authorities act voluntarily. Even if Brook is found on the mainland he cannot be lawfully detained. The girls went missing nearly eight weeks ago while their mother, Lucinda McDonald, was on honeymoon with her new husband. It has since transpired that Brook, whose daughters are both on his British Passport, got a Chinese visa from the embassy in London last December. Interpol is eager to track down his new partner, a Chinese woman who had been studying in the UK and returned to the mainland several months ago. Letters she sent to Brook's daughters have been traced to Shenzhen. Mrs McDonald and her new husband, Hector, have applied for single-entry Chinese visas and are expected to continue their search across the border this week. A Government House spokesman said the administration had been asked not to divulge details of the case because of its sensitive nature. 'We are liaising with the British Government in London and the British Embassy in Beijing. 'This whole matter revolves around events that have taken place in the UK and in China. We have become involved because Hong Kong was used as a transit point. 'We are aware of what is going on but, unfortunately, we in Hong Kong are limited as to what we can do. At the moment this is a matter concerning the British and Chinese Governments. 'We are taking an active interest in this case and will help where we can. The father has not been located in China but efforts are being made to find him and the children.' The Chinese Embassy in London was reluctant to talk about the case but confirmed Brook had been given a visa last December. Mrs McDonald dropped her daughters at her ex-husband's rented bungalow in Nottingham, England, on Boxing Day. But when the girls failed to call their grandparents to wish them Happy New Year, the McDonalds cut short their honeymoon in Sri Lanka and returned to the UK. Mrs McDonald divorced Brook three years ago and won custody of the girls. He was given visiting rights. As wards of court the children could not be identified by law. But last Thursday, a judge in London's High Court lifted a publicity ban, saying it was in the interests of both justice and the public that they be named. Police know Brook and the girls left England for Hong Kong on December 29. They travelled to China the following day. Brook is in China on a tourist visa and despite there being an international warrant out for his arrest there is little that can be done while he stays on the mainland. Lucinda and Hector McDonald flew with her mother to Hong Kong to search for the girls several weeks ago. He arrived back in the UK on Friday to have further talks with the Chinese Embassy in London and to negotiate a fee, believed to be GBP10,000 ($121,000), for their story with a tabloid newspaper.