In a major step toward normalizing relations, Soviet leader Mikhail S. Gorbachev has given the green light for direct flights between the Soviet Union and Israel, a senior Israeli official said Saturday.

The flights will begin within a month, said Yossi Ahimeir, a spokesman for Prime Minister Yitzhak Shamir. He said the Soviets did not provide further details about the arrangement, which by late Saturday had not been reported by Soviet media.The flights would accelerate the exodus of Jews from the Soviet Union to Israel. The Jewish state is already straining to accommodate more than 100,000 newcomers who have arrived since last year.

A senior Israeli immigration official, however, said the number of direct flights would initially be limited to about two per week each way, and thus would not immediately have a dramatic effect on the numbers of Soviet immigrants.

"But hopefully the number of flights will eventually be expanded," said the official, speaking on condition of anonymity. "We would like to be in a position in which the majority of Soviet Jews can come straight from the Soviet Union. It's easier and safer."

The immigrants now arrive via European transit points, and space is often limited. Even before the direct flights agreement was announced, estimates said the number of Soviet Jewish immigrants could swell to 1 million by the end of 1992.

Ahimeir praised the Soviet step as "a very positive development in the direction of strengthening and intensifying the relations between Israel and the Soviet Union."

He said it was another leap toward resuming diplomatic ties.