Paris — Thousands of Frenchmen and Solidarity supporters marched in the rain in Paris Oct. 12 to protest the outlawing of the Polish independent trade union Solidarity.
French President Francois Mitterrand, returning from an African tour on Monday, denounced the Polish government's move, saying it ''constitutes a new and dramatic blow at rights and liberties of the Polish man.''
But the most personal and anguished response in all France to the outlawing of Solidarity comes from the Polish community here.
Over the last two centuries France has been a refuge for Poles who rebelled unsuccessfully against repressive governments at home. According to the French Ministry of the Interior, the Polish community in France numbers some 74,000 Polish nationals and refugees.
Each generation has brought with it different political beliefs. But in what seems to be a remarkable show of unanimity, even the white-haired descendants of Polish nobility who left Poland after World War II sport ''Solidarnosc'' pins, as do the activists who left in 1968.
''Solidarity,'' said Krzysztoc Pomian, a Polish university professor who came to France in 1973, ''enjoys the support of 90 percent of Polish immigration.''
As in Poland, attendance in the Polish Roman Catholic Church here is high. Stanislas Ludwiczak, priest at the Polish church in Paris and a French citizen, makes no secret of his political sympathies and has placed a Solidarity poster next to his pulpit.
''For Poland,'' said Fr. Ludwiczak, ''we are a human presence. We show them they are not alone.''
Books about Solidarity and tape cassettes of political songs are on display outside the church every Sunday. Two trucks collect relief packages to transport to Poland.
''We are not only confident, we are sure that the movement will continue,'' said Solidarity spokesman Seweryn Blumstajn. Coordination committees of the Solidarity union have been established in eight European capitals, Canada, and the United States since martial law was declared in Poland last December.
Solidarity's Paris information office serves as a clearinghouse for clandestine publications coming from Poland. It also keeps lists of union members who have been interned or imprisoned. The foreign bureaus maintain contact with the underground movement in Poland and send back material aid to the families of imprisoned members.
Mr. Blumstajn said the coordination committees were urging Western trade unions to boycott the new unions in Poland.
France's Socialist government and French trade unions have been sympathetic to the plight of many Poles caught in France when martial law descended like a thunderbolt last December.
French refugee officials estimate that between 10,000 and 15,000 Poles are in France on tourist visas and have chosen not to go back. Since martial law was declared last year, only slightly more than 1,200 Poles have requested political asylum.
Many Polish nationals here are in limbo, unwilling to ask for political asylum and cut their ties with Poland, yet unable to go back to Poland, where they may face imprisonment. The French government has issued many of them temporary residence and work permits and ignored expired passports and invalid visas.
Mr. Blumstajn himself is one of those cases. A member of KOR, the dissident Polish intellectual group, he also joined Solidarity. He was in Paris on an official visit to the French Socialist trade union when martial law was declared. His name was on the list of people to be interned.
Former internees form the latest wave of Polish political immigrants to France. They are Solidarity members who were held in internment camps, then released and pressed by the Polish authorities to leave the country.
Stanislaw Woroch, for example, arrived in France Sept. 10. He has a bushy red beard and frightened blue eyes and wears a tiny gray Solidarity pin on the pocket of his shirt. A mechanic for the Polish railroad, Mr. Woroch was the head of the Solidarity chapter in his factory.
While he was in the internment camp the security services proposed to him that he leave Poland. Several months later he left for France. He does not want to go back. Woroch, his wife, and their young son are living in an immigrant absorption center, and he is learning French.