A two-day visit here of Assistant Secretary of State Thomas O. Enders has produced no visible progress toward resumption of U.S. military aid and sales to Chile, but before his departure for Washington last night, Enders said relations between the two countries continued to be "excellent."

Congress has conditioned the aid resumption on administration certification that the military government of President Augusto Pinochet has made "significant progress" in improving human rights, and has taken steps to "bring to justice" Chilean officials indicted in the 1976 Washington slaying of exiled Chilean diplomat Orlando Letelier and his associate, Ronni K. Moffitt.

Enders' trip here was designed in part to consult with the government over steps it has taken or could take to justify certification and reestablish the military ties that both Washington and Santiago want. U.S. Ambassador James Theberge, who presented his credentials to Pinochet Monday, told him that "President Reagan and the American people wish to have the best relations possible with you and the Chilean people."

But according to human rights groups and informed analysts here, little in the way of human rights improvement is to be found.

Enders met yesterday with officials from the independent Chilean Human Rights Commission and the respected rights divisions of the Roman Catholic Church. Both organizations maintain that while Chile improved human rights standards in the late 1970s, what they call a system of selective repression has been tightened gradually.

Military action against political opponents entered a new stage in 1978, a Human Rights Commission spokesman said, when "repression stopped being massive and indiscriminate and started being discriminate--they started selecting from among their potential victims."

"The idea is to maintain the fear they already had put into the population by maintaining a presence through selective repression that at the same time improves their international image," he said.

According to both commission and church files, there were more than 900 political arrests by Chilean security forces last year, 68 complaints by prisoners or their families of torture, 16 persons killed in alleged confrontations with security forces, and 67 expelled from the country or exiled internally.

The exiles include Jaime Castillo, the president of the rights commission and the lawyer for the Letelier family here, who was exiled shortly after a visit last August by U.S. Ambassador to the United Nations Jeane K. Kirkpatrick.

The first two months of this year, according to human rights files, there have been 174 political arrests, compared with 114 in the same period last year and 22 in 1980, and 14 complaints of torture. In all, human rights groups now say, 181 persons are under detention for political reasons and 300,000 exiles have been denied permission to return.

In recent weeks there also have been major incidents that human rights officials adduce as a deteriorating situation, including the slaying of a prominent labor activist and the continuing detention of two directors of the Chilean rights commission, one of whom allegedly has been partially paralyzed by electric shocks and other torture.

Chilean government officials have denied involvement in the death of Tucapal Jimenez Alfarao, a prominent labor leader who was promoting a common labor fund against the government, and have charged the human rights leaders with "illicit association," which means they were allegedly working as political activists.

In addition to these cases, human rights spokesmen here argue a disturbing trend toward psychological torture by security forces and a growing number of cases--16 were recorded during 1981--in which persons have been shot and killed by police during alleged terrorist confrontations.

In several instances, families of persons thus killed have charged that political suspects disappeared or were arrested several days before the alleged confrontation, and say that police staged the supposed shoot-outs.

On the Letelier case, Chile has refused to extradite the three military officials here, including former chief of intelligence Manuel Contreras, whom a U.S. grand jury indicted for complicity in the murders. A supreme military court last September found the officials innocent of the charges and closed the case.

The Chilean Supreme Court modified that finding in January, however, saying that while there was not enough evidence implicating the officials, charges could still be brought against them if new evidence emerged. Attorneys for the Letelier family have said that the government has declined to turn over information that could provide a basis for reopening the case.

Chilean government officials have said that Chile is facing an increased threat of terrorism from the West, involving the clandestine return here of political exiles. As evidence, they cite recent terrorist attacks, such as one on the president of the Supreme Court late last year, and on the home of a high-ranking Army official by unidentified terrorists.

Although U.S. officials who have supported the resumption of a military relationship with the Chilean government generally agree that no clear progress in human rights has been made in the past two years, Enders is said to be prepared to argue a case for overall improvement since 1976, the year of the Letelier-Moffitt killings.

Last December, Congress agreed to the administration's proposed lifting of restrictions on military sales and assistance imposed on Chile and Argentina during the Carter administration, but added the certification requirement.

Certification would permit not only authorization of a $50,000 initial military training program in the current administration budget for these countries, but also issuance of U.S. licenses for commercial military sales that are now prohibited.