A month after the airlift of Ethiopian Jews from Sudan to Israel was abruptly broken off, new efforts reportedly are being made to bring out the estimated 1,500 still in Sudan, amid fears for their safety.

Little is being said about these efforts, here or elsewhere, as those questioned note pointedly that public discussion of what was to have been a highly clandestine rescue effort last year led to its shutdown by an angry Sudanese government.

Israeli and Jewish organization officials refuse to discuss any current efforts to remove the remaining Falashas, as the Ethiopian Jews are called, although new fund-raising efforts are in progress among Jews abroad.

U.S. officials say only that they are "optimistic" that a way can be found out of the present impasse, and one said that there appeared to be no "big obstacles" in the way of gaining Sudan's permission to remove the Falashas.

Sudanese President Jaafar Nimeri told The New York Times in mid-January, two weeks after halting the airlift, that the Falasha refugees were free to leave Sudan provided that they did not travel directly to Israel. But a presidential adviser later discouraged any idea of a resumption of a large-scale airlift, saying that those with proper visas could leave on scheduled airlines bound for Europe.

At Khartoum University, when the airlift became known, wallposters denounced the government's collusion with the United States and its Israeli ally, accusing Nimeri of colluding with Zionist and imperialist forces.

The presidential adviser acknowledged that the airlift had not proved "very popular" with the Sudanese bureaucracy, but he dismissed the protests, arguing that "every Arab government has clandestine links with Israel."

Already there have been isolated signs that Sudan is helping some of the Falashas to leave. For example, sources said, a chartered plane landed on a blocked-off stretch of highway one day recently to pick up three Falasha families at government request. It could not be learned, however, where the Falashas were taken.

Present efforts to extricate the stranded Falashas apparently are taking place without the network of "spotters" that Israel had placed in Sudan to do the fieldwork for the airlift.

Informed sources said that since mid-January, Israel has ordered as many as 80 of the spotters -- many of them Americans or Ethiopians -- to leave, a move that, for many of the Falashas, dashed hopes of a speedy departure.

In the secret airlift, in which Washington played a major role at least in gaining Arab League member Sudan's acquiescence in the Israeli-sponsored operation, 7,000 or more Falashas, who had trekked from their age-old homes in Gondar Province in Ethiopia, were flown to Israel, where about 3,000 had gone in smaller groups over the years. Despite opposition from some conservative religious quarters, they have been accepted as Jews, based on a religious history believed to date to the Queen of Sheba.

Leaks by Jewish organization officials and Jewish publications in the United States and Israel prompted Israeli government disclosure of the operation early last month, and the next day it was halted by the Sudanese government, which had come under strong criticism here and in the Arab world.

Many of the Falashas still stranded in Sudanese refugee camps are relatively old and, since the disclosure of their presence, they have met with hostility and mistreatment from Sudanese and other Ethiopians, according to some refugee sources, although these reports could not be confirmed.

The absence of any visible effort to get them out of Sudan led one source to fret last week that the remaining Falashas have been "abandoned to their fate in a potentially hostile environment."

One Jewish official in the United States said this week that, based on accounts he had received of suffering and harassment on the part of the Falashas, he considered them "at grave risk" in Sudan.

He said, however, that their current health conditions apparently are not as bad as they were last summer, when lack of food, poor sanitary practices and unaccustomed exposure to lowland fevers killed about 1,500 to 1,800 Falasha refugees.

Many relief workers criticized American and Canadian Jewish groups and visiting Falashas who already had emigrated to Israel, saying that their enthusiastic encouragement prompted many Falashas to leave relatively peaceful and well-provisioned Gondar Province in Ethiopia en masse starting last spring and to seek refuge in Sudan without adequate logistical support.

The Falashas began arriving here six months before the larger flow from famine-devastated Tigray and Eritrea provinces.

Unlike those refugees, whose antigovernment rebel leaders established feeding centers along the line of march, the Falashas benefited from no such support system.

Some relief workers here say Israel intervened and asked the United States to organize the airlift as a result of the mounting death toll last summer; others suggest that the airlift resulted from the change in government in Israel that brought to office Labor Party Prime Minister Shimon Peres, who adopted the Falasha cause.

In any case, organizing such an effort in a predominantly Arab country where pro-Palestinian and anti-Israeli feelings run high proved time-consuming and led to extraordinary secrecy.

So intent were Sudanese and U.S. officials on maintaining secrecy that they detained some relief workers, a visiting photographer and a Canadian official at one of the major Falasha processing centers. Some relief workers also attribute what they called the "abrupt termination" of a U.S. aid contract with a Sudanese Roman Catholic relief agency to the secrecy effort -- an allegation that U.S. officials deny.

Nick Miscione, an American, and Gabriel Daniels, an Ethiopian-born U.S. resident, were taken into custody Dec. 10 by Sudanese security officials at Tawawa camp near Gedaref in eastern Sudan. Miscione was expelled six days later, according to other relief workers, and Daniels was held until last week, when he was allowed to return to the United States.

Both men worked for Sudanaid, the relief arm of the Sudanese Roman Catholic Bishops' Conference. After the arrests, relief workers here linked that incident with what they said was the cancellation by the State Department last September of a Sudanaid contract for refugee assistance at Tawawa. The workers suggested that the U.S. government sought to remove two knowledgeable witnesses from Tawawa to protect the secrecy of the Falasha operation.

Officials in Washington said, however, that the contract simply was not renewed at the end of the fiscal year, because the "work-generating" project it supported was not considered essential to "life-saving" needs at the camp.

Detained with Miscione and Daniels were a photographer and Yves Bernard, an official of Quebec Province who was in Sudan to check on Canadian-aided relief activities.

The photographer, on assignment for three British private relief organizations, reportedly aroused suspicion when he took photographs of four buses at the Tawawa camp.

In a telephone interview from Quebec, Bernard, who was detained for 30 hours, said, "I understood that we were not supposed to be there," and he added that he felt "lucky not to have disappeared." The photographer also was freed.

A U.S. Embassy spokesman confirmed that the Dec. 10 incident was connected to the presence of the Falashas, but he gave no further details. Relief workers said embassy staff accompanied Miscione to the Khartoum airport and returned his passport to him only when he was set to leave.

Tawawa, five minutes from the city of Gedaref, is convenient because it is just off a main highway easily accessible to the Khartoum airport. It thus became a major marshaling point for the Ethiopian Jews on their way to Israel.

By last November Tawawa and other camps near the Port Sudan-Khartoum highway acted as collecting points for Falashas staying in more remote camps in the bush. Buses accompanied by security police drove to Khartoum after dark, and between 2 and 5 a.m. almost daily, Falashas boarded chartered Belgian planes using a remote part of Khartoum Airport.

Even now such is the climate of fear among relief workers connected with private voluntary organizations that those interviewed insisted on anonymity. They said they fear any discussion of the exodus of the Falashas will compromise their relations with the Sudanese authorities, whose continuing good will is indispensable for their work.

They also said that the U.S. Embassy has the reputation of cutting off aid to voluntary agencies that run afoul of its directives.