In the first direct attack by rebel soldiers against relief workers in Ethiopia, two employes of the American relief agency World Vision were shot to death early this month in the dining room of their residence compound in the northern town of Alamata.

Western diplomatic sources said the attack marked the beginning of a new guerrilla offensive by the Tigray People's Liberation Front, a well-armed, highly disciplined rebel army that has been fighting for more than a decade in northern Ethiopia against the Addis Ababa government.

According to these sources, who are in contact with the rebels, the group has warned since the Alamata shooting that it does not want western relief workers in its area and that it will continue to attack them.

The warning threatens a U.S. Agency for International Development effort to feed 270,000 famine victims by moving food north beyond government-controlled territory into a region contested by the Tigrayan rebels.

"It appears that the TPLF does not want its people to get food from the government side," Fred C. Fischer, chief AID official in Addis Ababa, said today in a telephone interview.

While food supplies in northwest Tigray are adequate at the moment, Fischer said it is likely that the area will need large shipments of food aid in late April and May to avoid widespread famine.

The March 8 killing of the two World Vision workers, both of whom were Ethiopian nationals, puts the U.S. government in an awkward and politically embarrassing position, because it draws attention to discreet American ties to the rebels.

At the same time it is distributing food through World Vision in Ethiopia, AID is also working in Sudan to distribute food "through the back door" to famine victims in rebel-held parts of Tigray.

According to a Sudan-based official for the Relief Society of Tigray, an arm of the rebel front, that distribution is handled for the U.S. government through the American-based Lutheran World Relief organization. Lutheran World Relief, in turn, hands American food over to the Relief Society of Tigray, which trucks it across the Sudanese border into rebel-held areas of Ethiopia.

The U.S. connection to the rebel group has been tolerated quietly by Ethiopian government officials for more than a year.

In a statement on the Alamata shooting, the rebels have said that the death of the two World Vision workers was an accident resulting from their being caught in cross fire between rebels and government soldiers.

World Vision and AID officials in Addis Ababa, however, said today that the killings were deliberate and that there were no government soldiers within 20 miles of the incident.

"It is clear that the TPLF knew who they were killing," said Fischer, the AID official. "They were in a World Vision compound. They went into the World Vision dining hall. All the people identified themselves as World Vision employes, and they systematically shot them," said Fischer.

A senior World Vision official familiar with the shooting said today that five gunmen broke into the Alamata compound at 8 p.m. on March 8, while the staff was eating dinner. He said the gunmen forced people to lie on the floor while they ransacked nearby offices. As the gunmen were leaving, he said, they opened fire "indiscriminately."

"They wounded five of our people, killed one outright and one of the wounded died the next morning," he said. The dead were two women, a nurse in her mid-fifties and a nutrition assistant in her mid-twenties. The World Vision official said one man in the compound was kidnaped by the gunmen and later released.

World Vision, one of the largest private relief organizations in the world, has seen its Ethiopian program grow dramatically during the past year. It now has 1,600 employes in the country and a cash budget this year of $50 million.

The senior official of the California-based organization, who declined to be quoted by name, said that World Vision would continue with the Tigray feeding program despite the shooting, but that "we have to be far more involved in security."

Since the March 8 shooting, the rebel front has increased guerrilla violence sharply in the north-central region of the country known as "greater Tigray."

During the past week, relief officials said the rebels attacked eight large trucks traveling inland from the Red Sea to the port of Assab. All eight trucks were burned, and one driver was killed, the officials said.

The U.S. government also supplies food to rebel-held areas of Eritrea, in the far north of Ethiopia. That program, according to Fischer, has not been interfered with.