The shooting here last night of a U.S. Embassy employe was described today by a senior American diplomat as "clearly an assassination attempt."

"We cannot pin the blame on anyone at this time. But I would certainly refer you back to all the statements made by Col. Muammar Qaddafi himself," said the diplomat, alluding to calls by Libya for attacks against American targets before the U.S. bombing in Libya.

"This was not an accident. This was clearly an assassination attempt," said the diplomat, who refused to be identified by name.

In Washington, officials were believed to be making plans for the evacuation from Sudan of large numbers of Americans, mostly dependents of embassy staff members. The decision to withdraw the Americans apparently was out of concern over the shooting incident and an influx of Libyans into Sudan.

Wednesday night, however, the State Department declined to comment on reports that a U.S. pullout of dependents was imminent. "There are no plans for an evacuation," a department spokesman said.

The Associated Press quoted one administration official as saying the situation was one of "taking regular flights out," not a question of a military evacuation. There are about 200 U.S. officials in the Sudan and about the same number of dependents.

The State Department, meanwhile, warned Americans yesterday not to travel to Khartoum because terrorist activity poses "life-threatening dangers."

At midday today, before word of the shooting was circulated in the local media, about 10,000 Sudanese gathered in central Khartoum for a mass rally to denounce the U.S. bombing in Libya.

The victim, who worked on the embassy staff as a communications specialist, was shot once in the head as he drove home alone from his evening shift at the embassy, according to U.S. officials here.

One Sudanese witness to the shooting told authorities that several men in a white Toyota sped past the American's private car as he was driving near his home at about 10:15 last night. The witness said they fired five shots before racing away.

The American, whose name was withheld by embassy officials because of the U.S. Privacy Act, was identified by Sudanese police as William J. Cokals, 33. He was evacuated early this morning in an embassy plane to Jeddah, Saudi Arabia, where a bullet was removed from his head. He was reported in stable condition late today. He has no family in Khartoum, officials said.

The Sudanese government released office workers to attend the protest rally. It began in a holiday mood, with Sudanese secretaries, dressed in the flowing, snow-white gowns they wear to the office, strolling Khartoum's crumbling streets, chatting and holding hands.

But on a particularly hot and windy day, with the air chalky white from sand off the surrounding desert, the mood quickly soured.

Officials of the military government and leaders of the political parties that are to take control of the new civilian government at the end of this month all made speeches denouncing U.S. "aggression."

Sudan in the past month has received military aid from Libya in its war against rebels in the southern part of the country. Since it began receiving that aid, Sudan, which also is a major recipient of U.S. assistance, has become increasingly critical of the United States.

Sudanese Prime Minister Gizzuli Daffa-Allah told the crowd that all of Sudan's "material and human resources are under the request of Libya to face the American barbarian aggression."

After the speeches, most of the crowd left peacefully. But several hundred people then attempted to surround the U.S. Embassy. They were pushed back twice by Sudanese soldiers, firing tear gas canisters and wielding night sticks.

Near the front of the crowd of demonstrators were several Libyans who have been seen here in the past week with a delegation from Tripoli that came to Khartoum seeking political and economic "unity" between Libya and Sudan. Western diplomatic sources here estimate there are about 200 Libyan government employes in Sudan. These sources say that among them are several people trained and experienced in terrorism.