CIA Director William J. Casey said yesterday that Soviet leader Mikhail Gorbachev has launched "an intensified effort" to secure "bridgeheads" for spreading subversion and extending Soviet influence in the Middle East, Central America and Africa.

Speaking here to the annual conference of the American Israel Public Affairs Committee -- the pro-Israel lobby -- Casey said the Soviets have armed Libya and Syria in an effort to put a squeeze on Israel and the moderate Arab states in the region.

The Reagan administration has used Casey's Central Intelligence Agency to give covert support to insurgent forces in Nicaragua and Angola, and President Reagan and other administration officials have frequently blasted the Soviets while lobbying for aid to the contras, as the Nicaraguan counterrevolutionaries are known.

But Casey rarely makes public speeches. And an equally rare public attack on Gorbachev personally by any administration official comes at a time when the Reagan administration and the Soviet leader have been jockeying over the details of another summit conference this year.

Casey, in his speech and in frank answers to questions from the group, also said:

*Saudi Arabia has paid "lip service" to U.S. concerns about its funding of the Palestine Liberation Organization. He said Saudi leaders, host now to Vice President Bush, support the PLO and other terrorist-linked groups "for reasons of fear, intimidation, and pursuing their own foreign policy objectives."

*The Sandinista government of Nicaragua started an all-out campaign two months ago to destroy the U.S.-backed contras, including driving thousands of Miskito Indians across the border into Honduras during the past week.

*Cuban troops and Soviet advisers in Angola are "feverishly preparing a campaign, likely to be launched during this month, designed to wipe out forces resisting the Marxist government of Angola."

But Casey saved some of his strongest rhetoric for Gorbachev and the Soviets. "We have a new Soviet leader, Mr. Gorbachev, and already a hallmark of his regime is an intensified effort to nail down and cement these bridgeheads, make them permanent," he said.

The CIA director said the United States and its allies have succeeded in many places in slowing or halting Soviet aggression. But he said, "Today we are witnessing particularly intensive efforts to tilt the overall strategic balance against the West."

"We Americans have failed to see the interrelationships" between the Soviet efforts in different parts of the world, he said.

Casey did not specifically address terrorist bombings in West Berlin and on a TWA plane over Greece. But he said, in answer to another question, that "there has evolved over recent years a worldwide counterterrorist network based on active intelligence exchange" between the United States and Israel, European allies and moderate Arab countries.

"We do a lot of training, providing technical services to improve the capabilities of those services, and we collaborate with them in counterterrorism actions," he said. He did not elaborate.

Casey did criticize European nations for being slow to place economic and political sanctions on countries supporting terrorism. "We can only hope and I think believe that the recent outrageous character of terrorist acts will stimulate and strengthen cooperation of that kind."

Moderate Arab countries, as well as Israel, are threatened by terrorism, he said, noting that radical Arab groups hope "to polarize the Arab world so no accommodation can ever be reached." Casey said he thinks it is important to renew the Arab-Israeli peace process to deny the Soviets "a lever for entry into the Middle East."

In an effort to stall peace initiatives in the region, he said, Moscow might increase its support for Libya and back "a more aggressive Syrian military posture toward Israel, abandon Arafat and throw full support behind leftist and Syria-backed factions of the PLO." Yasser Arafat is PLO chairman.