The United States is consulting with congress about the possibility of selling military equipment to Morocco, the State Department said yesterday.

Department spokesman Hodding Carter III confirmed news reports that Morocco had asked to "buy certain military items." But, he added, the U.S. understanding was that Morocco's request involved only equipment that could be used for internal defense purposes.

Carter stressed that the discussions do not represent any change in the U.S. position of neutrality toward the dispute between Morocco and Mauritania over territory in the phosphate-rich western Sahara Desert.

The New York Times reported yesterday that the Carter administration was exploring the possibility of selling aircraft and helicopters to Morocco for use against guerilla forces seeking to make the western Sahara region independent.

Under a still-secret 1960 agreement, U.S. arms sold to Morocco can be used only for internal defense. As a result, any sales of the type now being discussed would require revision of the agreement in ways that meet congressional approval.

In another development, Hodding Carter confirmed a Washington Post story published yesterday that Mexico and Guatemala want to buy U.S. made F5 supersonic jet fighters. He refused to discuss details, and said the requests would be considered in the context of President Carter's policy of encouraging disarmament in the Western Hemisphere.

The President's national security adviser, Zbigniew Brzezinski, told a meeting of religious leaders at the White House yesterday that the president next week will announce a plan to reduce sales and grants of U.S. arms to foreign countries.

In a policy statement last May 19, Carter called for cutting the level of U.S. foreign military sales as a means of helping to put a brake on the international arms traffic. Nevertheless, the Defense Department has said that U.S. arms transfers will increase from $11.2 billion in fiscal 1977 to $13.2 billion in fiscal 1978