The head of the Nicaraguan domestic intelligence service announced today the arrest of two Interior Ministry officials who he said worked for the CIA. He also accused four U.S. diplomats who have served in the embassy here of being intelligence agents.

In a news conference, Sandinista commander Lenin Cerna, chief of state security, said 1st Lt. Reynaldo Aguado Montealegre and 1st Lt. Jose Eduardo Trejos Silva attempted to obtain information about several topics, including the command hierarchy of the state security system and about operations against the anti-Sandinista guerrillas known as contras or counterrevolutionaries.

Cerna also named four U.S. diplomats he said were intelligence agents: Bradley Cecil Johnson, former second secretary in the embassy's economics section; Benjamin B. Wickham, former first secretary in the political section; Stephen D. Murchison, first secretary in the political section, and Bonnie Sue Bennet, the vice consul.

Cerna did not describe precisely the diplomats' role or explain how they were identified as alleged intelligence agents. He did not clarify how much information had been passed or explain how the two Nicaraguans were caught.

"We have our own means," he said.

An embassy official confirmed that Wickham and Johnson had worked at the embassy and said they are no longer in Nicaragua. He said Murchison and Bennet are still in the country. But the official would not comment on the espionage charges.

"As a matter of policy, we do not comment on intelligence matters or alleged intelligence activities," the official said.

A knowledgeable source said U.S. Ambassador Harry E. Bergold Jr. was given a brief diplomatic note about the accusations during a meeting this morning with Vice Foreign Minister Javier Chamorro. The source said the Sandinistas did not ask for the expulsion of the two diplomats still in Managua.

State security chief Cerna presented equipment allegedly used by the two Nicaraguans, including cameras disguised as cigarette lighters and an ashtray with a compartment for hiding film.

During the press conference, Aguado Montealegre said he went to Miami last fall to visit his mother after being told by his family that she was dying of cancer. He said that while he was there, he was introduced to a man named William Perez, who said he worked for the CIA.

Perez said that the story of Aguado's mother's illness was a ploy to entice him to Miami and that he asked him to collect information from inside Nicaragua, Aguado said. He added that he agreed to do so because of threats against his family. He said before his return to Nicaragua in November he met with several other agents who instructed him on how to use espionage equipment.

He said he was promised permission to live in the United States and a $5,000 monthly payment into a Miami bank account.

The Sandinista newspaper Barricada said Trejos Silva, the other detainee, had been working for the CIA for two years. He did not appear at the news conference.