The Soviet government bluntly warned Israel tonight that the current Israeli invasion of Lebanon was affecting Soviet interests in the Middle East and demanded a withdrawal of Israeli forces from Lebanon.

"The Soviet Union takes the Arabs' side not in words but in deeds and is pressing to get the aggressor out of Lebanon," a Soviet government statement said. "The current Israeli policy makers should not forget that the Middle East is an area lying in close proximity to the southern borders of the Soviet Union and that developments there are bound to affect the interests of the U.S.S.R. We are warning Israel about this."

Despite the blunt warning to Israel that Moscow's political and security interests are affected by the invasion, the government statement did not specify any retaliatory actions. Diplomatic observers, however, suggested that the warning may foreshadow some form of Soviet involvement particularly if the Israelis continue their mop-up operations against PLO strongholds in Beirut.

Well-informed sources here said consulations were under way between Moscow and Damascus.

Syria, which is Moscow's key ally in the Arab world, has a treaty of friendship and cooperation with the Soviet Union. The Soviets also have been the main arms suppliers of the PLO.

In its statement, Moscow underscored its willingness to "do everything depending on it for a stable peace to be established in that area," but the tone of the statement was much sharper than previous official pronouncements on the current Lebanese crisis and appeared to reflect mounting concerns here about Israeli actions during the past 48 hours.

The Israeli invasion, the statement said, has turned the Middle East into "an even more dangerous center of international tension."

"The Soviet government demands that this brazen aggression be stopped," the statement said, accusing Israel of "perpetrating a criminal act of genocide."

A series of Tass dispatches immediately preceding the government statement today spoke about the possibility of a broader armed conflict and for the first time criticized "Arab states" for "observing indifferently the destruction of the Palestinians in Lebanon" by "Israeli fascists."

Tass said the Israelis were "following in the footsteps of Hitler's Nazis believing that the end justifies the means." It described as "brazen" a demand by Prime Minister Menachem Begin for the creation of a 25-mile security zone along the Israeli-Lebanese border.

The government statement expressed the concern for the alleged threat to Lebanon's independence. Charging collusion between Israel and the United States, it said, "The design to split up Lebanon and deploy on the captured Lebanese soil the so-called multilateral forces, the backbone of which would be formed by American troops, is becoming ever more evident."

The government statement tonight charged that Israel was trying to "drown in blood the struggle of the Palestinian people for their freedom and independence" and indirectly warned other Arab states that Arab disunity could subject one country after another to Israel's "diktat."

The Lebanese invasion, Tass said, is a direct result of U.S.-Israeli strategic cooperation. Its ultimate aim is to "impose Israeli-American diktat on the Arabs."

In carrying out these plans, Tass said, "Israel is using the fact that a number of Arab countries are virtually observing indifferently the destruction of the Palestinians in Lebanon."

[In Jerusalem, Israeli government officials withheld comment on the Soviet demands, Reuter reported. "We do not react officially to news reports and will wait to receive the actual text of the Soviet Union's statement, an Israeli Foreign Ministry spokesman told reporters.]