The United States, in a strong gesture of disapproval, yesterday recalled its ambassador to Chile because of that country's alleged failure to co-operate with the investigation into the 1976 murder here of Chilean dissident Orlando Letelier.

Letelier, an outspoken critic of Chile's military regime, and an American associate, Ronni K. Moffitt, were killed on Sept. 21, 1976, when a bomb destroyed their car in the heart of Washington's Embassy Row.

In announcing the U.S. action, State Department spokesman John Trattner said: "Ambassador George W. Landau is being recalled from Santiago for consultations with the State and Justice departments. The Chilean authorities have not been forthcoming on important requests for information in the Letelier-Moffitt murder case pending by the Justice Department for some time."

The United States has said the murders were planned in Chile by the former Chilean secret policy agency, DINA, and carried out here by DINA agents in collaboration with anti-Castro Cuban exiles.

Under U.S. pressure Chile expelled an American citizen, Michael V. Townley, who is now in custody here and who has admitted being the DINA agent who placed the bomb under Letelier's car.

Townley also reportedly has implicated in the plot three Chilean army officers who were assigned to DINA: Gen. Manuel Contreras Sepulveda, retired former chief of DINA and a close friend of Chilean President Augusto Pinochet; Lt. Col. Pedro Espinoza, former DINA operations chief; and Capt. Armando Fernandez Larios, who reportedly worked with Townley in bringing the bomb device to Washington.

Trattner refused to discuss the nature of the U.S. requests that the Chileans allegedly have not honored. However, reliable sources said the most important was a request that a key witness - apparently Larios - either come to the United States to testify before a federal grand jury or allow himself to be questioned by U.S. officials in a third country.

In addition, the sources said the United States feels Chile has not cooperated in efforts to obtain information from the government of Paraguay about an attempt that was made there to obtain U.S. visas for Townley and Larios under false names.

Other sources said the decision to recall Landau - a step that stops just short of breaking diplomatic relations - was made jointly by Deputy Secretary of State Warren M. Christopher and Eugene M. Propper, the assistant U.S. attorney heading the murder probe for the Justice Department.

However, the sources revealed, Justice Department officials were surprised and angered by the way in which the State Department, in announcing the recall, seemed to link it to controversies about human rights in Chile.

The Pinochet government, which took power in a bloody 1973 coup that included the killing of Marxist President Salvador Allende, has been accused of murdering, torturing and imprisoning its opponents. Letelier had served in the Allende government as defense minister and as ambassador to Washington.

When Trattner announced that Landau was returning to Washington, he added: "Ambassador Landau's visit will also give us a chance to review the human rights situation in Chile."

Under questioning by reporters, Trattner also said that a shipment of practice bomb parts for the Chilean air force, which has been held up in California because West Coast longshoremen refuse to load them aboard a ship, "will not be loaded while this assessment of the human rights situation is going on."

Justice sources protested privately that State had acted improperly in leaving the impression that the human rights and murder investigation questions were tied together.

By so doing, these sources said, the State Department had undermined Justice's contention that it is interested only in bringing the murderers to trial and not in Chile's internal politics. There recently have been escalating charges within Chile that Washington is using the murder probe as a pretext to topple the Pinochet government.

Reliable sources said the decision to include the language about reviewing the Chilean human rights situation in State's public announcement was made by Christopher, who oversees human rights policy within the State Department.

However, the sources were unable to explain why Christopher, who is a former deputy attorney general, felt the two issues should be linked or whether he had checked this move with Justice.

Chilean Foreign Minister Hernan Cubillos, who is in Washington attending the annual meeting of the Organization of American States, responded to the announcement of Landau's recall by charging that the United State was not cooperating with Chile's own internal investigation of the Letelier affair.

Another Chilean government source, who declined to be identified, said the Pinochet government had been informed of the decision to recall Landau last week. Yesterday's announcement, the source charged, had been timed to embarrass Chile in the midst of the OAS meeting.

In addition to Townley, five other persons, all Cuban exiles, have been charged so far in connection with the Letelier assassination plot. Three are in custody in the United States, and two others are fugitives.

All of the Cuban exiles are said to be members of the Cuban Nationalist Movement, based in northern New Jersey.