West German Chancellor Helmut Schmidt, caught in a debate with parallels to the argument over sale of U.S. AWACS planes, leaves Monday on a visit to Saudi Arabia without a government decision on a similarly controversial proposal to sell the Saudis West German tanks.

The debate here on a reported Saudi wish to purchase up to 300 Leopard II tanks and an assortment of other West German military equipment has raged for four months. It was thought Schmidt would bring the matter to a head before meeting Saudi officials on his trip.But the risk of a violent political clash should he push the sale apparently dissuaded him.

Arms exports generally arouse keen political interest here, where the warring past makes today's government particularly wary of shipping weapons to areas outside the Atlantic Alliance. A Cabinet decision specifically prohibits sale of West German arms to areas of tension such as the Middle East.

Further complicating a Saudi deal for the West Germans is the thought that their tanks in Saudi hands could some day be used against Israel, a fear similar to that expressed in Washington about the AWACS (Airborne Warning and Control System) radar surveillance planes. This offends the special sense of moral responsibility for the Jewish state felt by a number of West German legislators of all parties.

Competing against this concern are pragmatic West German business interest stressing more trade, jobs and oil, and envisaging an additional $9.2 billion annually from the next Saudi five-year economic plan if Riyadh gets the German arms it wants.

Economic ties already are strong. Saudi Arabia provides about a quarter of West Germany's imported oil. It is the third-biggest buyer of West German goods outside Europe. Half foreign business of West German building companies, moreover, is being carried out in Saudi Arabia.

Schmidt remains circumspect about any arms sale to Saudi Arabia. But he is believed to favor one, chiefly in the interest of bolstering the security of what the chancellor described today in an interview in Welt am Sonntag as West Germany's most important partner outside Europe and America.

Continuing to sidestep the swirl of politics, morality and business surrounding the Saudi deal, Schmidt told the newspaper that talk of an arms sale would not be a central topic during his two-day stay in Riyadh, which is expected to focus instead on expanding German-Saudi economic cooperation.

Schmidt indicated that a decision on the sale would have to await a full-scale review of Bonn's arms export policy. The Policy is expected to remain restrictive, but government officials have hinted it may be relaxed by a loophole provision That would permit arms sales to conflict regions if such sales would serve West Germany's national interests.

The government asserts it has received no official request from Riyadh for weapons. Preliminary talks, however, have been reported between Saudi representatives and Krauu Maffei, the Munich-based manufacturer of the Leopard II tank