Tempered by public realization that only massive emergency shipments of U.S. grain are preventing widespread starvation, anti-Americanism is on the rise in Sudan.

This paradoxical view of the Reagan administration reflects both resentment over its support for President Jaafar Nimeri and an alibi for Sudanese unwilling to take risks to overthrow him themselves.

Symptomatic of the mood is the militant denunciation of the Sudanese government and of the United States routinely carried out at the University of Khartoum by radicals safe in the knowledge that the police will not intervene on campus.

The government tolerates such blowing off of steam by communists and members of other banned political parties as a calculated safety-valve exercise.

Such is what one professor called "anti-American paranoia" that the United States is routinely accused of establishing military bases and even torturing prisoners here. At most, the United States appears to provide Nimeri with intelligence documents and satellite photographs useful in prosecuting the war against rebels in the south.

As a presidential adviser made clear in an interview, the regime propagates the proposition that the United States gives Nimeiri a free hand at home in return for his support of U.S. global strategic interests.

True or not, that view goes to the very heart of much Sudanese discontent with the United States.

"Why does Washington put up with this madness?" a Sudanese intellectual asked after denouncing amputations and other human rights excesses carried out in the name of the Islamic penal code, "when the Sudan is no Saudi Arabia sitting on endless oil reserves?"

"Why cannot the Americans let this Godforsaken country alone?" bemoaned a university professor, reflecting frustration with what many Sudanese perceive as their plight as a superpower pawn.

He argued that the United States views Sudan purely as a prowestern buffer protecting Saudi Arabian oil and unimpeded Egyptian access to the Nile against the radical threats posed by Soviet-backed Ethiopia and South Yemen and radical Libya.

But such oversimplication fails to take into account local realities, he argued.

For example, Sudanese support for Eritrean rebels fighting the Ethiopian government for more than 20 years predated Nimeri's rule and existed when he was pro-Soviet and they were pro-American.

Similarly, during Nimeri's pro-Libyan period, Col. Muammar Qaddafi handed over to Sudan prominent communists who had led the 1971 attempted coup against Nimeri. They were executed in Khartoum.

Thus, Libyan and Ethiopian support for the current rebellion in southern Sudan could be interpreted as yet another episode in continuing bad relations between neighbors rather than in East-West terms.