Soviet President Leonid Brezhnev's death evoked concern yesterday in world capitals that a protracted transition in leadership could cause Moscow's efforts to foster detente in Europe and reconciliation with China to stagnate.

Many analysts believe the aging Politburo members will strive to preserve a safe political consensus and thus will move with utmost caution in the realm of foreign policy until power passes to a new generation.

In Bonn, a Foreign Ministry official predicted that the absence of strong Soviet leadership could forestall any chances for progress in arms control negotiations or new initiatives to improve East-West relations.

"We may see a period of stagnation where the Soviets are not willing to move on anything for a while," he said.

While the Kremlin wrestles with the problems of succession, West German officials say the review of the Conference on Security and Cooperation in Europe accords, now taking place in Madrid in an atmosphere of contention, could conclude without results.

They also foresee continued paralysis in arms control talks being held in Geneva, which would cause NATO to proceed with deployment of Pershing II and cruise nuclear missiles in five European countries starting in December 1983.

British officials said they shared the belief that any major initiatives in Soviet policies at home or abroad would probably emerge only after a future leadership manages to consolidate power.

Brezhnev's passing was universally viewed as a milestone event, but opinion was sharply divided over its consequences.

Conservative voices in West Germany called for a more militant posture in the West, while Social Democrats warned against a confrontational course that might strengthen the hand of Kremlin hard-liners.

Alfred Dregger, floor leader for the ruling Christian Democrats, said, "A phase of insecurity now seems unavoidable . . . the West must remain all the more resolute in questions of security so that the new Kremlin leadership makes no miscalculations."

In contrast, Social Democratic party chairman Willy Brandt insisted that "it is all the more important that we in the West maintain a reliable and consistent policy directed toward cooperation and not confrontation and use chances for disarmament and securing peace."

In Peking, diplomats said news of Brezhnev's death provoked intense debate among Chinese officials over the level of representation for the deceased leader's funeral, news agencies reported.

Brezhnev's last important move in foreign policy was a plea to Peking to settle disputes and restore ties between the two Communist powers by reviving negotiations that were aborted by China three years ago when the Soviets invaded Afghanistan.

The first round of the talks concluded in Peking three weeks ago and were expected to resume in Moscow this winter. It is unclear, however, whether Brezhenv's death will cause a postponement of the second round.

"There is uncertainty about how fast they [the Chinese] should appear to be moving toward the Soviets," a diplomat explained. "They feel their action [on representation at Brezhnev's funeral] will be interpreted by the Kremlin as a strong indication about China's sincerity toward the talks.

Peking reported Brezhnev's death without comment, but government leaders in other capitals coupled testaments to his leadership with praise for his pursuit of detente.

West German Chancellor Helmut Kohl hailed "the important contribution Secretary General Brezhnev made to treaties and accords signed between the Soviet Union and West Germany which created the basis for a better relationship between our countries in the future."

Italian Prime Minister Giovanni Spadolini, in his message of condolence, said that Brezhnev had helped "our continent cope with the danger of an outbreak of fighting."

French President Francois Mitterrand mourned "this great leader of the Soviet Union, whose eminent role in the world will be remembered in history."

In London, Britain's cooler relations with Moscow were reflected in Prime Minister Margaret Thatcher's comment that Brezhnev's death "will be a serious loss to the Soviet Union."

India's Prime Minister Indira Gandhi, whose country has become an increasingly important ally for the Soviet Union in the Third World, praised Brezhnev as "an outstanding statesman of our time."