To the amazement of many Mexicans President Jose Lopez Pertillo's anticorruption campaign has started to crack the ranks of "untouchable" high officials.

Last week, the director general of customs arrived at his office to find the door sealed and guarded by federal police, who told him he had lost his job.

A Cabinet minister, the undersecretary of education and the head of the National Coffee Institute all have been jailed on charges ranging from fraud to embezzlement.

In the past few months, more than 100 lesser officials have been put behind bars. Dozens of others have been fired.

In a country where corruption is a way of life and where people take it for granted that every public official has his price the sight of high government ministers in jail has left many Mexicans bewildered.

The idea that a major clean-up is taking place is still not accepted by the public at large. Many Mexicans dismiss the current campaign as a temporary political which hunt against officials from the previous administration - a ploy to gain credibility for the new government.

Nevertheless, Lopez Portillo - who has publicly called corruption "the cancer of this country" - has begun to move against his own appointees.

Persons close to the Mexican president say he feels the crackdown against corrupt officials is the only way to break the vicious circle of cynicism, lack of faith in government and general disrespect for the law.

The driving force in the current campaign is the tough new attorney general. Oscar Flores, who is pursuing corrupt civil servants with the same zest, he displayed in earlier crackdowns on leftist guerrillas and narcotics traffickers.

After arresting the popular under-secretary of education, Eugenio Mendez Docurro, Flores told an interviewer: "We'd grab more of them if they weren't so clever. Not everyone leaves fingerprints like traceable checks."

Far more inclined to cooperate with the U.S. Justice Department than his predecessor, Flores also has been working with Washington to identify American businessman and Mexican officials involved in payoffs by U.S. companies.

These investigations, which have been secret so far, may produce the first criminal actions against American companies resulting from the recent enactment by the U.S. Congress of the Foreign Corrupt Practices Act.

One of the cases being investigated on both sides of the border, according to officials, involves the rent and subsequent sale of two DC10 aircraft to the Mexican national airline Aeromexico.

Another probe, authoritative sources said, is focusing on the large-scale smuggling of Mexican coffee into the United States.

Several high officials of the National Coffee Institute have been charged with embezzlement of nearly $100 million, in connection with the contraband coffee trade. All have denied the charges.

The wave of arrests has unquestionably shaken the Mexican bureaucracy.

With federal inspectors swooping down on government officials around the country, insiders say a number of officials have scurried for cover.

These include a class of job holders known here as "aviators" - persons who land at government offices only long enough to collect paychecks for the fictitious positions they have been placed in by influential relatives or friends.

Accounts of the crackdown have been reported in spicy detail in the Mexican press.

"It's like seeing all your wildest nightmares suddenly come true," one political commentator wrote.

But for all the publicity, knowledgeable Mexicans remain skeptical of the long-range impact of the anticorruption campaign.

A front-page story in a local newspaper suggested recently that Lopez Portillo's drive to keep pesos from disappearing into the pockets of the politicos has a way to go.

Through paying varying amounts of money to low-level bureaucrats. The reporter wrote, he managed to obtain "four driving licenses and three military credentials without once showing identification of any kind."