The Soviet Union continues to supply spare parts and ammunition to North Yemen, which received $500 million in emergency U.S. military aid last spring, but there is no evidence of a new arms deal between Moscow and that sensitive Arabian peninsula country, according to State Department officials.

Informed sources said reports of a North Yemen-Soviet arms deal recently have been denied in diplomatic exchanges with the Yemen government at "a very high level," apparently a reference to President Ali Abdullah Salah.

There is no doubt, according to U.S. officials that the Soviets consistently have offered additional military equipment to North Yemen. Moscow was the traditional source for the country's arms before the United States began the emergency supply, financed by Saudi Arabia, last spring. More than 100 Soviet military advisers are reported to remain in North Yemen.

In addition to the continuing supply of spare parts and ammunition for their Soviet weapons, North Yemen is known to have purchased tanks from Poland recently.

The North Yemeni military buildup is parallel to a similar buildup in its rival state, South Yemen, which is more closely linked to the Soviet bloc and has received large shipments of new weaponry.