Foreign investors start to fear a bubble in the air

Foreign investors are keeping a watchful eye on new opportunities emerging from China's surging stock market; but an increasing number are also starting to warn against the possibility of a growing bubble, in what has become world's fastest-growing stock index.

Their key concern relates to the unreasonably high price-to-earnings multiples of the stocks leading the growth of the A-share market, warning that prices have become detached from fundamental values.

"A lot of these firms already have very high PE multiples, meaning a lot of work still needs to be done to meet their expectations," said Robert Davis, senior portfolio manager at NN Investment Partners.