US Probe Prompts French Crisis. INSIDER TRADING: OUT IN THE OPEN

THE scandal looked typically French. Two close friends of President Fran,cois Mitterrand are accused of using inside information to make a $10 million profit on the sale of American National Can Co. to the French aluminum firm Pechiney. Both deny the charges. In the past, a few telephone calls and some swift backstage maneuvering in high places caused similar charges of political corruption to fade from the headlines.

But this time, an unexpected actor destroyed the expected scenario: the United States Securities and Exchange Commission. Its independent investigations have forced a political crisis here, embarrassing the Socialist government and causing officials to consider more rigorous policing of Paris's stock markets.

``If it weren't for the SEC, there would be no scandal,'' said Chantal Hazan, a reporter covering the case for French television. ``In the past five years, our authorities have investigated 100 insider trading cases - and brought only four to trial.''

The French stock market watchdog, the COB, cannot bring charges against insider traders. It is dependent on the Ministry of Finance and only has the power to ``advise'' the state prosecutor to bring charges.

These judicial weaknesses allow manipulation. French politicians, both conservatives and socialists, are widely suspected of manipulating stocks. When the conservatives privatized many state-owned companies between 1986 and 1988, many of their friends managed to buy controlling interests. When the Socialists returned to power, they vowed to break these ``hard stones'' of conservative investors.

A new battle came over the Soci'et'e G'en'erale, France's third largest bank. An investor group led by financier Georges P'ebereau and backed by several large government institutions started buying Soci'et'e G'en'erale shares. The takeover bid failed. But the raiders apparently made a profit of about $100 million.

A COB investigation turned up no wrongdoing. But critics smell a cover-up. Without the SEC, the Pechiney affair would likely also have been forgotten.

In November, France's state-owned aluminum company bought the American National Can Co., a subsidiary of Triangle Industries. Just before the transaction, Triangle's stock price soared.

The SEC suspected manipulation and notified the French government that it was launching an investigation. Only then did the COB launch its own investigation, which uncovered that two of Mr. Mitterrand's longtime friends, Max Theret and Roger-Patrice Pelat, purchased large blocks of Triangle stock. Both insisted the timing was a coincidence.

As a state-run company, Pechiney kept the French Finance Ministry informed of its negotiations to buy American National Can. Press reports suggested that Alain Boublil, the Finance Ministry chief-of-staff, released information improperly. Mr. Boublil resigned last week, protesting his innocence and filing libel suits.

Mitterrand has pledged to respect the COB's findings when they are made public at the end of the month. In private, Elys'ee officials do not seem too worried by the developments. ``Up until now, this hasn't hurt us in the public opinion polls,'' notes one official. ``Confidence in the President is up.''

Analysts suggest that the reason for this indifference is a widespread feeling that all politicians are corrupt. The French never understood the US preoccupation with Watergate or later with Irangate.

``We still admire Richard Nixon as a strong, reliable leader who was brought down by insignificant political intrigue,'' says Philippe Moreau Defarges of the French Institute of Foreign Relations. ``When it comes to politics, we just don't think in terms of morality.''

Although most French officials insist they approve of US actions, some suggest darkly in private that there is ``a conspiracy'' to destabilize their government.

But the long-term effect may be salutary. Finance Minister Pierre B'er'egovoy says the French will strengthen the COB and sign an agreement with the SEC to share insider trading information. Until now, the SEC lacked access to French financial records.

The upshot will be important, both for Washington and Paris. As foreigners invest massively in the US, the SEC must show that US financial markets cannot be manipulated by foreigners who operate outside of its reach. And as Europe prepares to integrate its market, French officials feel they must show that they are ready to break the corrupt bonds between politics and money.