France, Aug. 15 -- The cybercrime unit of the Paris Public Prosecutor's Office is investigating the fraudulent extraction of data from a state-operated personal information system, following an attack described by tax officials as more sophisticated than previous incidents.

The investigation has been entrusted to France's Office for the Fight against Cybercrime, known as Ofac.

Prosecutors said the inquiry also covers suspected participation in a criminal conspiracy aimed at preparing an offence punishable by at least five years in prison.

The attack allowed hackers to extract data relating to 678,000 users of France's tax system, including both private individuals and companies.

Tax authorities said the incident was more complex than ...