A delegation of U.S. Roman Catholic bishops urged President Carter yesterday to demonstrate U.S. concern for human rights in El Salvador by continuing the suspension of military aid to that country and by halting the deportation of Salvadorans here illegally if their repatriation would be politically hazardous.

The president promised to consider the matters, Washington Archbishop James A. Hickey said.

On a related matter, Bishop Thomas C. Kelly, general secretary of the National Conference of Catholic Bishops, said the president agreed to release the report of a special commission appointed to investigate the deaths of four women missionaries in El Salvador earlier this month.

The commission, led by William Bowdler, assistant secretary of state for inter-American affairs, and William Rogers, who held the same post under presidents Ford and Nixon, reportedly found no clear evidence linking the murder of the women to government forces.Some Catholic groups in this country, particularly the religious orders to which three of the slain women belonged, have been pressing for public release of the Bowdler report so they could evaluate the thoroughness of the investigation.

Immediately after the murders, the United States halted more than $25 million in military and economic aid to El Salvador. Last week, after the Bowdler commission reported its findings, the State Department reinstated the $20 million economic assistance program but left the $5 million military aid program in suspension.

Hickey yesterday said that he and Kelly gave Carter "our urgent recommendation that military aid not be resumed" in case such action "would be seen as supporting those who do violence in El Salvador."

Even before the Dec. 4 murders, Catholics in this country have registered growing concern for the mounting violence and human rights violations in much of Latin America.

In recent decades, the Roman Catholic Church has moved from unblinking support of Latin American governments, no matter how corrupt, to a near total identification with the poor and oppressed. As a result, the church itself has increasingly come under fire. Priests and nuns have been killed, and in El Salvador earlier this year, Archbishop Oscar Romero was slain while saying mass in a church.

Kelly yesterday said that one reason U.S. Catholics have "gone public" with their protests now is to support Romero's successor, Bishop Arturo Rivera y Damas. "Normally we would do these things privately," said Kelly of the White House visit and a conversation last week with Secretary of State Edmund Muskie. "But we feel he [Rivera y Damas] has to have a lot of public support."

Kelly said the bishops have also expressed their concerns about humans rights in Latin America to Richard Allen, President-elect Reagan's national security adviser. He said the transition team "seemed very responsive to our concern."

A spokesman for the Immigration and Naturalization Service said the agency has no estimate of the number of Salvadorans illegally in this country. Some sources estimate there may be as many as 20,000 persons from El Salvador in the Washington area alone.

The INS spokesman speculated that few of the Salvadorans who come here do so for political reasons. "They can apply for asylum" if they fear repatriation would endanger their lives, he said, "but not very many do that . . . They're here because there's no money and no jobs there."