'turtles'

delayed including Chinese shares in its benchmark emerging markets index, a move that might have brought billions of foreign dollars to China's markets.

Former officials said most of the returnees left due to frustration over their lack of influence over policy, limited opportunities for promotion, and low pay. Others spoke of resentment from colleagues.

Some were effectively forced out by the fallout from Beijing's anti-corruption drive, which led to salary cuts for senior staff and a campaign against "naked officials" - those who move family members and assets overseas in case the official is arrested. "They can get high pay outside at lower risk, higher return. Why not?" said Oliver Rui, professor of finance at the China Europe International Business School in Shanghai.