The Pentagon, saying it was "taking a lot of flak from Israel and its supporters," sought yesterday to explain why the AWACS radar surveillance planes planned for sale to Saudi Arabia would be good at defending against air attack from Iran or other countries but would not threaten Israel.

Defense officials claimed the Saudis would be sending the planes on "suicide missions" if they attempted to fly near Israel's border during a Mideast crisis because the Israeli air force could shoot them down before they could assimilate and relay information gathered by the craft's radar.

Furthermore, U.S. officials said an agreement is being worked out with the Saudis to give the United States a say in how AWACS aircraft are used when Americans are aboard.

That U.S. role would be in effect even though the Saudis would officially own the Airborne Warning and Contral System planes after August 1985, when the first of five planes is schedules to arrive if Congress approves the sale.

On the other hand, these officials said the Saudis should be able to train at least one of their own AWACS crews by 1986, raising the prospect that the Saudis could have at least some freedom of action in the air.

U.S. military and civilian technicians would be needed to support and maintain the planes on the ground for the forseeable future, giving the United States an important check on potentially risky AWACS operations.

Vague understandings about Saudi control in the air are adding to the controversy surrounding the sale decision. AWACS planes basically are flying radar stations whose electronic eyes peer over borders and can spot the approach of small enemy jets 175 miles away and larger aircraft as far as 360 miles away.

Israel claims that the Saudis could use AWACS planes to watch the Israeli air force and provide vital intelligence informaiton to other Arab air forces, perhaps gravely compromising Israeli security in a crisis.

The sale plan is generating great controversy in the Senate and, as part of an administration effort to ease concern, the Pentagon held a briefing for reporters yesterday. Rules for the briefing specified that officials not be identified.

The officials said the AWACS planes were meant to defend against air or sea attack on Saudi oil facilities from Iran or other countries across the Persian Gulf. AWACS would provide enough warning time so that U.S.-built F15 fighters, equipped with new types of U.S.-built Sidewinder missiles, could intercept attackers before they reached oil fields on the Saudi's gulf coast.

The new missiles can fire from a position facing an attacker, rather than only from behind, an aid to stopping attackers before they reach the oil fields.

The United States is selling the Saudis fighters, missiles and aerial-refueling tanker planes that can keep an AWACS plane airborne for twice its normal 11-hour flight time. Officials said the tankers also can refuel U.S. Navy jets.

The planes will not carry the kind of advanced intelligence-gathering equipment that allows monitoring of other nations' electronic and communications traffic. Nor will they contain special radios resistant to enemy jamming now carried by U.S. versions of the plane.

Under questioning, officials said they would be "very upset" if even these "sanitized" versions of AWACS planes fell into Soviet hands during any type of revolution in Saudi Arabia.

The officials siad the Soviet acquisition of an AWACS plane would not be "crippling" in terms of compromising U.S. technology and that the Carter administration had done a similar analysis about such a problem when considering an AWACS sale to Iran in 1977.

The United States did lose new F14 jet fighters and Phoenix missiles in Iran when the late shah was overthrown.

Officials said that it is "theoretically possible" for the Saudis to ask another country, such as France, to supply AWACS intelligence equipment being withheld by the United States.

But, they said, the Saudis would have great difficulty doing so without the United States finding out about the attempt and moving to stop it.

Similarly, they said, if the Saudis tried to transfer to other countries the ground terminals that AWACS planes use to relay their radar information, the United States would withdraw its equipment and support. Use of crews from other countries also would not be allowed.

The officials said that by operating in the northernmost corner of Saudi Arabia, AWACS radar could see all of Israel. But, they maintained, with so much normal air traffic in the region, it would be difficult to spot an Israeli air attack.

Officials also said that, unless the Saudis set up an elaborate joint training and command system with other Arab air forces -- another move the United States likely would learn about -- there would be no time to digest and use whatever information AWACS planes gathered before they became easy targets for Israeli fighters.