PANAMA CITY, AUG. 1 -- Faced with continuing opposition from Panamanian business and political groups, the government of military strongman Gen. Manuel Antonio Noriega appears to be intensifying a campaign against what it sees as three main sources of criticism: the press, the Roman Catholic Church and the U.S. Embassy.

A campaign against the press spread to the international news media this week and has resulted in the expulsion of a Panama-based correspondent for the Reuter News Agency, Thomas Brown, a 24-year-old American. Brown was summoned by immigration authorities yesterday and given 24 hours to leave the country "voluntarily" on grounds that he did not have proper accreditation.

Brown showed authorities a press credential issued by the Interior Ministry June 3 and valid for one year, but they refused to reverse the decision. Brown left today on a flight to Mexico in accordance with a Reuter decision not to contest the expulsion order.

No specific reason was given by the government for expelling Brown, whose articles have often appeared in a local English-language newspaper. A journalists' association of Editora Renovacion S.A., a chain of publications controlled by Noriega, Thursday formally asked the government to expel Brown for "violating the international code of ethics with his tendentious news items."

In recent days, some journalists have reported receiving anonymous threatening phone calls, and Noriega-controlled newspapers have accused correspondents of spreading "sedition."

Yesterday, Noriega himself lashed out at foreign reporters after a ceremony at the tomb of the late Panamanian leader, Gen. Omar Torrijos, who died in a plane crash six years ago.

Noriega called foreign reporters a "plague" and responded to questions by telling five western correspondents over and over, "Respect Panama." Wearing a dress military uniform with four stars on his shoulderboards, a high-peaked cap and polished black boots with silver spurs, the 49-year-old commander of the Panama Defense Forces marched past his questioners several times as his bodyguards jostled the reporters.

Later, Noriega appeared in civilian clothes at a large annual rally honoring Torrijos and pumped his fist in the air repeatedly as speakers denounced alleged U.S. "intervention" in Panama and led the crowd in chanting, "Not one step backward." Government supporters also shouted slogans against John Maisto, deputy chief of mission at the U.S. Embassy, who has been a particular target of the Noriega regime because of his background as a diplomat in Manila and head of the State Department's Philippines desk during the popular upheaval that ousted president Ferdinand Marcos last year.

A Noriega-controlled newspaper, Critica, this week called Maisto a "recognized enemy of the Panamanian people" and the "mastermind of the destabilization against our government."

It accused him of being an opposition "adviser" who was trying to "apply the 'Filipino plan' in our country" -- a reference to the U.S. role last year in pressuring Marcos to fly into exile. Critica Monday published a front-page photograph of Maisto, called for his expulsion and threatened to publish his home address.

The attack on Maisto coincided with what appears to be an intensifying anti-U.S. propaganda campaign here. On Wednesday the Noriega-controlled press accused the United States of "violating Panamanian sovereignty" by installing a secret "space base" to communicate with satellites without government permission. The U.S. Embassy said the installation referred to is actually a station of the Foreign Broadcast Information Service that has been operating here for years.

The Panamanian government also reacted strongly this week to a U.S. Embassy statement that urged it to "end all intimidation and censorship of press reporting immediately." The statement was issued in response to the government's indefinite closure of three opposition newspapers a day before a military assault Monday on the house of a leading Noriega critic, retired Col. Roberto Diaz Herrera.

An independent radio station was also closed down, and broadcast media were warned to curtail coverage of opposition activities or risk losing their frequencies.

The Panamanian Foreign Ministry Wednesday sent a protest note to U.S. Ambassador Arthur Davis, condemning the statement on press censorship as interference in Panamanian internal affairs.

The Foreign Ministry warned that further public statements of that kind would be considered "hostile action against the Panamanian government."

The Roman Catholic Church also has come under criticism for statements urging the government to lift press censorship and free prisoners captured in the July 27 raid on Diaz Herrera's house.

In a communique to be read in churches Sunday, Panama's archdiocese called for an end to "intimidation by military force" and to "the arbitrariness of laws that prohibit for some what is permitted for others."

"The economy, already hurt, will not endure much more," said the statement signed by Archbishop Marcos McGrath and other church leaders. "Violence is tending to spread in a dangerous spiral." it warned.

In an apparent effort to put the church on the defensive, the government Thursday publicized a letter that it said was sent by 700 prisoners, most of them black, to Auxiliary Bishop Oscar Brown, who has been instrumental in church efforts to ascertain Diaz Herrera's condition and secure the release of 45 of his followers.

Brown, who also is black, yesterday saw Diaz Herrera at a location he would not disclose and reported that the former colonel appeared to be in good health.

At least 32 of Diaz Herrera's followers were still being held in the Modelo Prison here and in a penal colony on the island of Coiba, church sources said.

The letter from the 700 common criminals, jailed at the Modelo Prison, accused the church of concentrating on the plight of predominantly white, middle-class Panamanians arrested recently for opposition activities.

The letter appeared to fit in with a government campaign to emphasize racial and class divisions between the businessmen and professionals who are in the forefront of the opposition and the poorer Panamanians whom the regime claims to represent, political analysts said.