Portions of this article were deleted by Israeli military censors. the delays would confront Israel's Air Force with a temporary loss in combat readiness, the new U.S.-built Israeli air bases in the Negev desert will be fully operational when the Sinai is returned to Egypt on April 25, according to senior Israeli military sources.

This strategically located air base in northern Sinai is being evacuated at a dizzying pace, like its sister base at Etzion, near the Gulf of Aqaba, and the new Ovda and Ramon air bases in the Negev are far enough along in development to be usable now and may be officially opened in a few weeks, the sources said.

Israeli Air Force officials said that runways, taxiways, parking ramps and aircraft shelters at Ovda and Ramon have been completed and that some fighters have already been deployed there. The sources, under Israeli censorship restrictions, cannot be identified, and they agreed to discuss the Sinai turnover only if they were not quoted directly.

While construction of some support facilities at both Ovda and Ramon has fallen behind schedule, the sources said, the delays will not affect the Air Force's capabilities at the two bases.

Under the terms of the Egyptian-Israeli peace treaty, Israel is scheduled to return to Egypt on April 25 the remaining occupied portion of the Sinai, a swath of desert stretching from El Arish, on the Mediterranean coast, to Sharm el-Sheik, on the Red Sea. To compensate for the loss, the United States agreed to build the two new bases in the Negev, inside Israel, with a grant of $800 million to cover most of the $1.04 billion cost. Israel is to build a third Negev air base at its own expense, but it is not expected to be completed for several years.

Development of the two bases has been marred by charges between Israeli and U.S. construction officials of shoddy workmanship, inferior materials, disappearing equipment and incompetent contractors. Some Israeli engineers have charged that with only 2 1/2 years to build the bases, the consortium of U.S. contractors, called Negev Air Base Contractors, sacrificed quality in the rush to meet the deadline.

Normally it would take four or five years to complete an air base of this size but the U.S. contractors had to speed work to meet the treaty schedule.

Israeli military sources said that while some support facilities are up to a month behind schedule, the delays do not pose operational difficulties for the Air Force. They said, for example, that the timetable for transporting equipment from Eitam to Ovda and Ramon had fallen behind because, in some cases, there were no storage facilities at the new bases.

The sources said contractors had promised to complete half the family housing units at Ovda by last August, but fell a month behind schedule, causing inconvenience for service families with children to enroll in base schools by September. The second half of the base housing will be completed nearly a year before its promised April 1983 date, however, although it will not be needed then, officials said.

During the awkward period between now and April 25, officials said, the Air Force will use the completed runways at Ovda and Ramon, and, if necessary, can still use the runways at Eitam and Etzion, even though support facilities there have been dismantled.

Under the peace treaty, Israel agreed to leave behind for the Egyptians fixed structures with no military significance, while dismantling and removing most prefabricated buildings for use at other military installations.

The Air Force plans to destroy the bases' underground facilities for sheltering aircraft during bombing attacks.

According to the peace treaty, Egypt can use Etzion and Eitam as civilian airports and for light military planes and helicopters but not as strategic or tactical bases. Israel is attempting to negotiate an agreement with Egypt in which Etzion would be used as a civilian airport for European charter flights to the Gulf of Aqaba resort city of Eilat.

The Eitam air base, located in barren desert and holding no commercial promise, is to be used as the main base for the U.S.-sponsored multinational peacekeeping force that will patrol the Sinai after April 25.

U.S. construction engineers have already moved into the barracks here to prepare for conversion of the base for the multinational force, which is expected to include 2,500 troops from about seven nations. About 1,000 of the troops are to be stationed here.

Military sources here said that surrendering Eitam will be particularly difficult for Israel because the base was designed for expansion and would have been the largest and most technologically advanced air base in the Middle East.

Moreover, the officials said, the hundreds of miles of flat terrain around the base offered a superb training facility.

Squeezed into the much less spacious Negev, Israel's Air Force will be have to yield valuable air space because of restrictions against training over densely populated areas of central Israel and over artillery and armor practice ranges in the Negev.

The Air Force had seven practice bombing ranges in the Sinai but will now have far fewer, sources said. Also, they said, navigation training will suffer, without the challenge of pinpointing navigation points in the vast Sinai, and such training over the Mediterranean is of little value.