A prominent Salvadoran Lutheran pastor from the eastern provincial capital of San Miguel was assassinated yesterday, and a church official said he had no doubt that the killing was a "political murder."

No group took responsibility for the killing of Rev. David Ernesto Fernandez Espino, and it was not clear if he was killed by forces of the left or the right.

A statement released by Rev. Medardo Gomez, president of the Lutheran Synod of El Salvador, said that Fernandez, who was in charge of church activities in El Salvador's eastern provinces, had been found dead yesterday afternoon on an isolated hillside about six miles south of San Miguel.

Concepcion de Fernandez, the priest's widow, said by telephone today that her husband had been shot once in the head and struck by seven machete blows.

There was no immediate indication who had killed Fernandez. But Wayne Steinert, of White Salmon, Wash., who worked with him as a representative for Lutheran World Relief, said today he had no doubt the killing was a "political murder."

When he last saw Fernandez last Saturday, Steinert said, the priest "expressed tremendous concern of being caught between the right and the left."

Fernandez said that just after he had held a graduation ceremony for the small vocational school he ran that had turned into a eulogy for the late Lt. Col. Domingo Monterrosa, the former 3rd Brigade commander here who died in a helicopter crash last month.

According to church officials, Monterrosa had been invited to attend the graduation ceremony. After his death, members of his family and his successor, Lt. Col. Miguel Mendez, were invited. At the graduation, which was attended by about a thousand townspeople, Monterrosa's mother and brother spoke to honor the late colonel.

At least one fellow Lutheran said he thought Fernandez had invited Monterrosa, and later his family, because he was trying to open lines of communication to the military to make his work with refugees from the civil war easier and safer.

"The church lives more or less in constant terror here," said the Lutheran. "In the polarization of El Salvador, anyone who works with refugees is seen as a suspect by the right."

In the past year and a half Lutheran church workers have run afoul of the country's military authorities twice, and church officials have alleged that their workers have been harassed, arrested, tortured and jailed as a result.

One such instance occurred in April 1983, when Gomez, who is also pastor of the Resurrection Lutheran Church in San Salvador, and "The church lives more or less in constant terror here. In the polarization of El Salvador, anyone who works with refugees is seen as a suspect by the right." -- a Salvadoran Lutheran Dr. Angel Ibarra, who ran the church's refugee health program, were arrested by the National Police as they drove back to the capital from the international airport.

Gomez was held by police for five days, while Ibarra, according to church sources, was apparently interrogated, accused of providing food and help to guerrillas, tortured, then thrown into the capital's Mariona Prison, where he stayed for six months before being freed and fleeing to Mexico.

Last November, the National Police also arrested Gomez's secretary, Maria Santos Grande Garcia and her brother, Ramon Grande Garcia, who was the church accountant. The secretary was released after 15 days of interrogation that church sources said involved electric shock torture. Not only was the brother thrown into prison, but his father and two other brothers, who had nothing to do with the church, also were arrested. All were freed six months later and fled into exile abroad.

Church officials have no explanation for why their workers have been terrorized except to say they suspect it is because of their relief work with refugees fleeing the civil war in the countryside. Many right-wing Salvadorans, including many in the military, consider refugees from guerrilla-controlled areas to be guerrilla sympathizers.

Fernandez's church in San Miguel was one of numerous Lutheran distribution points for food and medical care for refugees.

Concepcion Fernandez said she last saw her husband Tuesday at about 7 p.m., when he said he was going out for 15 minutes to attend the street fair commemorating the city's patron, our Lady of Peace. He never returned home.

Early Wednesday, at about 5 a.m., however, Fernandez was reported to have driven his Toyota van into the street in front of his mother's house, honked the horn, then exchanged greetings with her when she came outside, saying that "he had to go on a mission," according to church officials.

In the car with Fernandez were two men who some sources said were wearing uniforms while others said they only looked military.

Two hours later Fernandez's car was found empty, its key still in the ignition, not far from his mother's house. The car was under guard by government soldiers.

Church officials said that friends of Concepcion Fernandez reported seeing the vehicle at one point inside the city garrison of the Arce Battalion but when she went to inquire about it, and her husband, she was told "in strong language" that the car and her husband had not been held by government troops.

In his statement about the killing, Rev. Gomez said: "The Lutheran Church has no information about who might have committed this murder.

"We condemn this act of violence and all acts of violence that have plagued our nation," he added. "The war in El Salvador continues to take our country's best children."