With U.N. forces conspicuously absent, Israel formally returned to Egyptian sovereignty another 2,500 square miles of stark Sinai Desert today.

The swift, simple ceremony, with Bedouins looking on, marked the second phase of withdrawals agreed to in the Egyptian-Israeli peace treaty signed in Washington on March 26. Although of little economic or strategic value, the land's return was hailed as another highly visible sign that the peace treaty is being carried out on schedule.

"It is in fact a step forward on the road to peace," said Brig. Gen. Dov Shimon, who headed the Israeli military delegation at the ceremony.

Egyptian troops standing in the scorching sun at this oasis in Wadi al Nasr, or victory valley, cheered as Shimon's Egyptian counterpart, Brig. Gen. Seaif al-Din Abu Sneif, hoisted the Egyptian flag after Israel's Star of David was lowered.

It was the first time Egypt has had formal control of the area -- near the Abu Rudeis oil fields on the eastern shore of the Gulf of Suez -- since Israeli armored troops stormed across the Sinai in the 1967 Middle East war.

Recovering Egypt's occupied territory is President Anwar Sadat's top priority in his peacemaking with Israel. Under the treaty, Israel is to withdraw to a line stretching from El Arish on the Mediterranean to Ras-Mohammed at the southern up of the Sinai by November. Assuming the negotiations on Palestinian autonomy continue without a breakdown, the withdrawal is to be completed within three years. The parcel of forbidding desert sand and barren black rocks transferred today contains some manganese mines and other mineral deposits with modest commercial value, Egyptian officials said, but only a handful of depleted oil wells geologically connected to the nearby Abu Rudeis oil fields.

Its return, however, gives Egypt full control of the main road connecting Abu Rudeis to Suez City at the northern end of the Gulf of Suez, where the Suez Canal enters the gulf. Egypt recovered the oil fields from Israel in 1975 but had shared use of the road with Israel under U.N. supervision.

More important than the military or economic value of the land, in any case, was the symbolic value of Egypt recovering sovereignty over its occupied Sinai Peninsula. Sadat repeatedly has taunted his Arab opponents by telling them that Egypt at least is resuming control over its territory while they are still talking about it.

In that spirit, Bedouins -- who tend to drive trucks now as often as camels decorated their vehicles with signs proclaiming themselves "heroes of war and heroes of peace." In fact, there is no record of the Bedouins having taken any significant part in the modern warfare that has scarred the Sinai four times in the last 30 years.

Signs of that warfare were visible along the road from Suez: the carcas of a crashed helicopter, the skeletons of incinerated trucks and a few abandoned tank shells.

United Nations Emergency Force soldiers still manned crossroads and flew the U.N. flag at their outposts along the way, although they stayed away from the turnover ceremony.

The 4,500-man UNEF force mandate ran out at 6 a.m., local time, and news reports said its commanders received orders to cease operations. It is widely expected, however, that the forces should take UNEF's place.

Military analysts in Cairo say it would take UNEF some time to wind down operations even without other considerations. A Foreign Ministry spokesman in Cairo Predicted the pull-out would take at least three months. By that time, he assured questioners, a solution will have been found to the dilemma posed by Israel's rejection of a U.S.-Soviet proposal to replace Unef with unarmed troops from the United Nations Truce Supervisory Organization.

[Before the ceremony, a bomb blast at a bus station north of Tel Aviv wounded 12 persons, according to Israeli police. Palestinian commandos in Damascus, Syria, claimed responsibility Reuter reported.] CAPTION: Picture, Israelis fold their flag at ceremony in Bir Nasseb returning Egyptian land. AP