While the reasons behind China's detention of Hong Kong academics Li Shaomin and Xu Zerong remain a mystery, their cases have highlighted the risks and challenges of doing research on the mainland.
Local universities offer no guidelines for academics on research trips in China, and university representatives said that had not changed despite the arrests.
But the arbitrary manner in which arrests can be made in China is of serious concern to some academics.
Since the detentions, Anhui native X L Ding, now teaching at the Hong Kong University of Science and Technology, has deferred his plans to carry out studies on economic reforms in China this year. 'There are no unifying, explicit rules on how academics should go about doing research in China,' said Dr Ding, an expert on mainland economic reform.
When on the mainland, he only conducted interviews and rarely sought out official data, which he dismissed as propaganda. 'It's a pity I'm not going there for my research, but that's life - life is full of regrets,' he said.
A Hong Kong-born veteran researcher at the Chinese University said some academics here had exercised more caution and become more selective in their research topics since 1997.