GEORGE SOROS’s reputation for moral integrity and financial acumen was tarnished yesterday when he was fined €2.2 million (£1.4 million) for insider trading by a criminal court in Paris.

The tribunal found the billionaire financier guilty after deciding that he had abused privileged information in connection with a botched attempt to take over the French bank Société Générale in 1988.

The fine given to Mr Soros by Anne-Marie Foncelle, the presiding judge, was seen by lawyers as comparatively low, and will inflict greater damage on his image than on his bank account. It merely corresponded to the profits he made from dealing in Société Générale shares in 1988.

But in backing the prosecution’s claims that Mr Soros had been either unscrupulous or careless, or both, Mme Foncelle inflicted an unprecedented penalty on a man never before condemned for financial irregularity.

The blow was all the greater for the tribunal’s decision to throw out similar insider trading charges against his co-defendants, the Lebanese businessman Samir Traboulsi and the former French Finance Ministry official Jean-Charles Naouri.

Last night the financier reacted with fury at his conviction and said he would appeal. “I am astounded and dismayed by the court’s ruling,” he said. “I will appeal the decision to the highest level necessary.

“Let me repeat now what I have maintained from the start: at no point was I in possession of inside information regarding Société Générale. The charges against me are unfounded and without merit.”

Before the hearing, in the Paris Criminal Tribunal in November, 72-year-old Mr Soros said he was “certain” to be found not guilty. Yesterday Mme Foncelle read out a short, written ruling and imposed the €2.2 million fine for which the state prosecutor, Marie-Christine Daubigney, had called at the earlier hearing.

Mme Daubigney said Mr Soros was privy to inside information after being approached by the French financier Georges Pebereau, who asked him to participate in a raid on Société Générale in 1988.

But instead of throwing his weight behind M Pebereau’s bid for the bank, Mr Soros acted illegally by buying shares on his own behalf, the prosecutor said. He then sold them when their price rose as the attempted takeover became public, the court heard.

Giving evidence, Mr Soros said he had never received inside information, since M Pebereau’s plans were common knowledge in financial circles from the outset.

“I think I know what is an insider deal and what is not,” he said.

His lawyer, Maitre Bernard de Granruts, said Société Générale was one among many recently privatised French companies in which Mr Soros had bought a stake at the end of the 1980s: “He is not a follower. Indeed, his decisions are usually followed by others.”

After a financial career that reached its zenith when he made $1 billion (£665 million) as sterling fell out of the European exchange-rate mechanism a decade ago, Mr Soros has turned to philanthropy, using his fortune and his foundations to help developing countries.

He and his co-defendants denounced the trial as unfair because of the 14-year delay in bringing the case to court.