Messier continues to protest his innocence

Mr Messier was detained by Paris police on 21 June as part of a probe into share buybacks and sales in late 2001.

Four other people, including Vivendi's ex-finance chief Guillaume Hannezo, are already under investigation.

Under Mr Messier, Vivendi ran up huge debts and losses to fuel acquisitions, before he was ousted in July 2002.

He then spent more than a year fighting to win a $21m (�11.6m) severance payoff, before finally agreeing to forgo it.

Under the French criminal justice system, all five are now one step short of being formally charged.

Mr Messier is forbidden from contacting the other four, and will have to put up bail of 1.35m euros ($1.64m; �900,000) as surety against possible future fines.

Time limit

The move by the French financial police forms part of an inquiry into four events during Mr Messier's tenure as Vivendi chief executive.

Vivendi Universal has sold off much of its media empire

During that time, he transformed the group from its utilities base to focusing on telecoms and media.

That change of emphasis is at the heart of three of the actions on which the examining magistrates are concentrating: suspicions that the firm may have padded its results by treating partly-owned telecoms firms as if it owned them outright.

The fourth revolves around the buyback of 21 million shares shortly after the 9/11 attacks to support the stock price.

Investigators want to discover whether that was in breach of stock market rules banning such actions within 15 days of the release of results.

The shares were sold in December, shortly before the stock price fell.

At the time, Vivendi was struggling to contain the debts run up as a result of the acquisitions made to turn the group into a media powerhouse.

In the wake of the massive debts and losses Mr Messier's successor, Jean-Rene Fortou, has sold off a huge swathe of Vivendi's assets - including its US entertainment business, which went to NBC.

'Rules relaxed'

In a statement issued on Wednesday, Mr Messier hotly denied the charges.

He noted that the US Securities and Exchange Commission had authorised unlimited share buybacks after 9/11, and that the French authorities had "at the same time relaxed their rules".

The decision to buy the shares was "in the interest of non-speculating shareholders, so as not to leave the field clear for excessive market movements".