The police across France have detained more than 250 people and confiscated some 5,000 videocassettes in their largest operation to date to fight child pornography.

Among the people charged with possession or trafficking in pornography involving minors, the police said, are two school directors, two teachers and several others who work with children.

The police said those detained were all men, from different walks of life. ''No social class has been spared,'' a police official said. ''They are mainly married professionals. Some apparently made the videotapes, others distributed them and some just bought them.''

The crackdown on Wednesday and today involved no fewer than 600 police officers, an indication of the Government's alarm about sexual abuse of children. The action also appears to be a response to growing public indignation in France and elsewhere about the recurrent reports of kidnapping, rape or incest involving the very young.

Specialists say they are not certain whether the number of such crimes has risen sharply or whether the cases have simply become more notorious as it has become more socially acceptable to report or discuss such abuse publicly.

The police raids were coordinated by a special task force based in Nice, where investigators said they discovered the first evidence of an apparently well-organized child pornography network.

For four months, the police said, they watched exchanges on sex sites of Minitel, the state-owned on-line service, obtained codes of access to mailboxes and, through arrests, gradually found extensive address lists of suppliers and buyers.

The police actions are certain to have wide support. French news organizations gave much attention to the killing of four children by a pedophile that shook Belgium last year.