West German Chancellor Helmut Schmidt delivered a forceful appeal today for continued East-West cooperation in politics, trade and arms control.

In a state of the nation address to the West German parliament, Schmidt hit hard his favorite themes of balance, continuity and dependability in East-West relations and struck a significant contrast with the antidetente tenor of the new Reagan administration.

He welcomed Soviet President Leonid Brezhnev's recently expressed interest in visiting Bonn later this year, took a cautious view of the Polish situation and said he is assuming that Washington and Moscow will "in the relatively near future" resume negotiations to limit nuclear missiles in Europe. Schmidt also faces increased domestic opposition to a NATO decision to place medium-range nuclear missiles in West Germany. t

"The more intensive are relations between East and West, and the better relations are between the United States and the Soviet Union, the better it will be for us Germans," said the leader of this front-line NATO country that among Western nations has the deepest economic and humanitarian interests in relations with the East as well as an abiding security interest in ties to the West.

Appearing to rebut remarks made here earlier this week by U.S. Defense Secretary Caspar Weinberger about the failure of a decade of detente to curb Soviet arms, Schmidt said: "anyone who says detente is to blame for everything -- that it was detente that encouraged the Soviets to build up armaments -- should ask himself what Soviet armament would have been like under the conditions of cold war."

At the same time, Schmidt qualified his appeal for detente by stating it should not mean neglecting the need for military parity.

Including what for him was an unusually pointed attack on the Soviet Union, Schmidt blamed Moscow for disturbing international peace and upsetting the balance of military power in Europe. The remarks seemed intended primarily to counter spreading pacifist sentiment in West Germany.

"The horizon of world politics darkened toward the end of the 1970s, above all because the Soviet Union ignored important principles of international coexistence," Schmidt said. He cited the Soviet military buildup in Europe, the invasion of Afghanistan and "the creation of new military and political dependencies in Africa and elsewhere."

Focusing on the Soviet arms buildup, Schmidt noted that in 1960 the United States had 50 rockets facing 290 Soviet ones. The American weapons were removed in 1963, he said, but the number of Soviet missiles grew to 610 by 1970.

Today, the chancellor continued, the Soviets have more than 600 missiles of several types in Europe capable of carrying a total of more than 1,000 nuclear warheads while, Schmidt concluded, "there is nothing on the western side of Europe -- except for 18 French missiles -- that can compare with this."

It was to correct this imbalance that NATO countries decided in December 1979 to station 572 U.S.-made Pershing II and cruise missiles in Europe beginning late in 1983. Concurrently, the West offered to negotiate limitations on such weapons with the Soviet-led Warsaw Pact.

Initial U.S.-Soviet talks took place for a month last autumn in Geneva. Moscow has maintained that its missile buildup aims simply to offset other so-called U.S. "forward-based" nuclear systems, meaning U.S. air- and sea-based systems around Europe. The Soviets insist that these systems be included in the negotiations along with the new planned NATO missiles, which the United States opposes.

Schmidt sharply rejected the Soviet position today. He said the Soviet nuclear presence in Europe "is in no way balanced by [U.S.] aircraft or sea-based weapons." Adding that Moscow's nuclear superiority in Europe "represents a serious political threat" that cannot remain.

With growing opposition to the new NATO missiles from antiwar groups and the left wing of his own Social Democratic Party clearly in mind, the West German leader also renewed his government's backing for the early resumption of arms limitation talks. Schmidt said that on the basis of recent NATO consultations and Bonn Foreign Minister Hans-Dietrich, Genscher's trip to Moscow last week, he is going on the assumption that the U.S.-Soviet talks in Geneva will be resumed "in the relatively near future."

However, yesterday Weinberger linked the likelihood of further talks to a reduction of tensions around Poland, and U.S. defense experts say there is considerable analysis left to do before a definite date for resumption of negotiations with the Soviets can be decided.

On Poland, Schmidt said "everyone knows that an attempt to interfere with force" there would "change the world." He urged both East and West to avoid action that could "heat up" the situation. "In the future we in the West will only be able to give Poland the help that it needs to overcome its great economic problems if a climate of cooperation in Europe is maintained," Schmidt said.

At present, the West German leader said it is important for West Germany to keep Soviet confidence as well as Western confidence. He said Bonn would maintain "limited but dependable" cooperation with the Soviet Union and other Eastern European countries. He said President Reagan and French President Valery Giscard d'Estaing agreed with his view of the need to keep a dialogue going with the Soviets especially in times of crisis, and stated that he and Brezhnev are now discussing possible dates for the Soviet leader's visit to Bonn sometime this year.

At the same time, Schmidt stated that "West Germany belongs to the West," which guarantees Bonn's security.

"There is no security in Europe without the United States," he said. "President Reagan and his administration know that they can count on the readiness of the federal government for extensive and continuous cooperation -- as we count on them."

Schmidt said that "an intensive, promising process of consultation" had begun with the new U.S. administration that has already shown a "high level of agreement on all important questions." He said he was looking forward confidently to his visit to Washington May 20.

A large portion of Schmidt's speech dealt with relations between West and East Germany, which have been strained since the troubles in Poland boiled over last summer. The chancellor said he was ready to reschedule a twice-postponed meeting with East German Communist Party leader Erich Honecker once the international situation permitted.

The outlook for trade between the two Germanys, which rose by 18.7 percent in 1980 to a record $5.5 billion, looks "favorable," Schmidt said. He ran through the list of other advantages -- visits to the West by East German pensioners, phone calls from the West to East Germany, and religious, cultural and sport contacts -- which a decade of eased tension has brought.

"If the situation in Europe is good," Schmidt said, "we Germans could greatly benefit from it. If it is bad, it will be the German nation that suffers most.

"We realize our geographic and historical situation [indicates] to a very special degree the duty to keep peace. . . . To us peace is a state that continually must be renewed among states -- by means of keeping and restoring balance on the lowest possible military level, by means of negotiations and pacts, by creating mutual trust, by cooperation.

"Balance is an indispensable precondition," Schmidt continued. "But balance alone is not enough. It is also necessary to talk to each other."