In a move that could signal a tougher new U.S. attitude toward EL Salvadors military regime, the State Department has sent two officials to look into allegations of widespread human rights violations in that tiny Central American nation.

A department spokesman said the two officials, who left yesterday, are Mark L. Schneider, deputy assistant secretary of state for human rights, and Sally A. Shelton, deputy assistant secretary for inter-American affairs.

The spokesman described their mission as consulting with the government of President Carlos Humberto Romero on "the general situation in El Salvador, including political and human rights questions."

However, reliable sources said their purpose is to help determine whether U.S. policy, which has been generally supportive of the Romero regime, should be revised in light of charges that El Salvador's government has become increasingly repressive in its treatment of political dissidents.

In particular, the sources added, Shelton and Schneider are expected to make a recommendation on whether the United States should support El Salvador's request for some sizable loans from international lending sititutions.

These proposed loans, which are due for decisions shortly, involve requests to the World Bank for $23 million for telecommunication expansion and up to $12 million for vocational training. In addition, El Salvador has asked the Inter-American Development Bank for loans of $13.8 million for a cattle development program and $3 million for planning.

Under the Carter administration's human rights policy, Deputy Secretary of State Warren M. Christopher has been charged with determining whether rights violations are occurring in an applicant country before U.S. representatives ot the lending agencies are instructed on whether to vote for the loans.

The sources said the United States probably will vote for the vocational training loan in the World Bank because it meets administration guidelines about providing direct benefits for El Salvador's poor and needy.

But, They continued, Schneider and Shelton recently advised Christopher to take a harder look at the other requests.

They reportedly were concerned by escalating unrest and violence in El Salvador during recent weeks. Several U.S. church and human rights groups have accused the Romero regime of trying to tamp down the disorders through a campaign of murder, illegal detentions and intimidation of government opponents.

In recent years, El Salvador has been plagued by seesawing terrorism from rightist and leftist groups, which has included several murders. A year ago, the government's moves against the leftists, which included the shooting of protesters and the expulsion of several priests, caused widespread criticism in the United States.

Washington reacted then by blocking El Salvador's request to the Inter-American Development Bank for a $90 million hydroelectric loan. However, U.S. policy shifted after Romero, a rightists army general, took office in July amid charges he was elected fraudulently.

Romero initially made several conciliatroy moves toward the leftists, and the State Department withdrew its objections to the hydroelectric loan as an encouraging gesture.The aim, department sources explained, was to bolster his hand against ultra-rightist pressures and to foster more liberalization.

In another potentially controversial move involving human rights in Central America, the State Department quietly has approved the use by Nicaragua of $160,000 in unexpended military sales credits for equipment to be used in a military hospital there.

Department officials said the money will serve a humanitarian purpose because the hospital also is used by civilians. They added that the ban on transfers of military equipment to Nicaragua, in force for the last year because of human rights factors, is being continued.