Beijing is preventing GlaxoSmithKline's head of finance for China from leaving the country, as police accuse the British drugmaker of bribing officials and doctors, a spokesman for the drugmaker said on Wednesday.

The travel restrictions on Steve Nechelput were imposed at the end of June and he continues to carry out his work in China, as well as being free to move around the country. He has not been questioned, arrested or detained by police, the spokesman added.

Police have accused GSK of transferring up to 3 billion yuan ($489 million) to 700 travel agencies and consultancies over six years to facilitate the bribes. In response, GSK said it was deeply concerned by the allegations, which it called "shameful."

China is increasingly important for big drug groups, which rely on growth in emerging markets to offset slower sales in Western markets where many former top-selling medicines have lost patent protection.

IMS Health, which tracks pharmaceutical industry trends, expects China to overtake Japan as the world's second-biggest drugs market behind the United States by 2016.