The Nicaraguan government today charged that two U.S. military officers were found traveling without permits in a restricted war zone and suggested that they were involved in "espionage activity."

In a protest note to the U.S. Embassy, the Nicaraguan Foreign Ministry said the officials, Col. Alden Cunningham, the embassy's military attache, and Capt. Barbara Sims were found Tuesday traveling near the town of Siuna, a remote area in north central Nicaragua that has been a focus of combat between the Sandinista Army and guerrilla forces.

The note said the officials, who did not have permission to travel in the region, were told by Sandinista military authorities to "leave the zone immediately."

"The Nicaraguan government . . . has all the right to assume the said people were engaging in espionage activity," the note said.

An embassy official would not confirm receipt of the protest but said that Cunningham, like many embassy officials all over the world, frequently traveled outside of the capital to see what was going on in the country. "We cannot comment on the question of espionage activity," the official said.

Other knowledgeable sources said that Cunningham was traveling in the area.

Beyond the letter of protest, which charged that the trip "constituted a clear provocation to create interventionist actions against Nicaragua," there was no indication that the Nicaraguan government planned any action against the officials or the embassy.

Earlier this year, Managua charged that four U.S. Embassy officials, two of whom had already left Nicaragua, were working for the CIA. Two Nicaraguan Interior Ministry officials also were arrested as CIA agents.