Michael V. Townley, the American accused by U.S. authorities of participating in the 1976 assassination of Chilean diplomat Orlando Letelier, was selected by the Chilean secret police to arrange the assassination because of his contacts in the Cuban exile community in Miami, his Chilean wife said yesterday.

Mariana Callejas de Townley said she received a message from Townley through his parents telling her he was cooperating fully with U.S. authorities and has named 10 persons who he said either ordered or carried out the Letelier assassination in Washington.

While she refused to say whether Townley told her the 10 names, she said she presumed that the ex-chief of the secret police, Gen. Manuel Contreras, was on the list.

Callejas has been the source of much of what is known about her husband, most of the information accurate but some of it not, and she appears to have great influence over her husband. She said she was the one who urged Townley to cooperate with U.S. prosecutors once he was deported to the United States.

She also appears to know many of the the details about the assassination although she has been unwilling to reveal certain facts she believed could damage her husband if he is brought to trial.

Townley is being held in the United States without bail on a charge of conspiracy to murder. [His lawyer, Seymour Glanzer, could not be reached for comment last night.]

Callejas said that her husband is now cooperating with U.S. prosecutors because he believes Chilean President Augusto Pinochet's statements that the government here wants whoever might have been involved in the Letelier assassination to be brought to justice.

She said her husband had never been urged by any Chilean official to reveal who allegedly ordered him to go to Miami and arrange for Cubans to carry out the purported mission. Townley was simply taking Pinochet at his public word, she said.

Pinochet has said publicly several times that his own conscience is clear and that he does not believe that anyone in his government ordered the assassination.

Now that Townley, according to his wife, has told the United States which members of Chile's old secret police force, the Directorate of National Intelligence (DINA), ordered the assassination, it remains to be seen how the Chilean government will react.

In recent days, government spokesmen have been narrowing their definition of what constitutes the government, and, at one point, even suggested that DINA was really a part of the military and not part of the government at all.

Government spokesman have also said that Townley may have been hired on a "contract" basis for certain services but that he was never a full time DINA employe. Callejas has said that her husband has received regular monthly checks of $400 to $500 from DINA since joining the Chilean secret force in 1974.

Callejas said her husband had told her that he was "following higher orders" from his superiors in DINA when he traveled to Miami in September 1976. Letelier was killed by a car bomb in Washington on Sept. 21, 1976.

Callejas said she did not know whether the alleged order to arrange for Letelier's assassination had come personally from Gen. Contreras or from a middle-level military official in the secret police.

She said Townley was chosen for the mission to the United States because he had become familiar and friendly with Cuban exile groups while living in Miami in 1973. At that time, Townley - who has lived more than half of his life in Chile and says he considers himself a Chilean patriot - was himself somewhat of an exile.

He had fled Chile because of charges that he participated in a commando operation aimed at the government of former Chilean President Salvador Allende. The clandestine raid, in the southern city of Concepcion, was against an electrical installation there and led to the death of a night watchman.