Israeli Foreign Minister Shimon Peres said Tuesday he and Secretary of State George Shultz agreed that the Soviet Union is now willing to join the stalled Mideast peace process.

Peres, emerging from an hour-long meeting with Shultz prior to a call on President Reagan, said U.S. officials told him the Soviets had increased to 1,400 the monthly exit permits given to Jews wishing to emigrate."There is no doubt" that one can learn from that about "increased Soviet liberalism" toward the U.S.-orchestrated peace plan for Arab-Israeli talks, Peres told reporters.

The Soviet role in the peace plan will be a topic at the superpower summit in Moscow later this month, Peres said, adding that he and Shultz had devoted their entire talk to the Kremlin's position.

Peres said he had told the Soviets at meetings last week in Spain and in Hungary that "they have to do more and in a more determined fashion" to boost the flagging peace initiative.

"I told them that their fear of the Arab reaction is exaggerated because the Arabs need peace talks no less than we do," he said. The Soviets have expressed concern privately that their radical Arab allies might be angry if they joined the peace process.

Syria, a close ally of Moscow's, rejects the Shultz plan but the more moderate Jordan has said it welcomes Soviet participation.

Peres said he had been told in his talks here that the Soviets have expressed concern about the proliferation of surface-to-surface missiles in the Mideast in the wake of revelations that Saudi Arabia had bought such rockets from China. The United States and Israel have criticized the clandestine Saudi purchase of the intermediate-range CSS-2 missiles.

Reagan is expected to try and infuse the Shultz plan with new life after the mid-April deadline for its implementation passed with neither Israel nor Jordan making up their minds whether to reject or accept it.

Reagan, who has warned Israel and Jordan against rejecting the peace plan, is expected to stress his view that the U.S. blueprint is the only solution to the five-month rebellion in which 180 Palestinians have been killed by Israeli troops.

But neither side held out much hope that Reagan would be able to budge the plan initiated earlier this year by Secretary of State George Shultz.

General elections scheduled in Israel for November are expected to serve as a referendum on the plan.