French stock market regulators are investigating unusual share price movements in France Telecom and several other CAC40 blue-chips, amid concerns that unknown market players could be profiteering from a wave of rumour and speculation.

The move comes as regulators in other countries voice concerns at the potential for market abuse in exceptionally buoyant takeover markets. A recent study by the UK's watchdog, the Financial Services Authority, estimated that, in spite of its efforts to stamp out abuse, questionable share price movements ahead of bids remained as prevalent as in 2000.