Despite its role as North Korea's closest ally, China appears to be reluctant to exert influence over Pyongyang's intrigue-ridden efforts to reunify with South Korea and may privately prefer that U.S. troops remain in the South for the time being, diplomats here say.

The latest round of reunification talk attempts and border incidents in Korea focuses attention once again on China's curious relations with its small, northeastern neighbor.

While enjoying high-level Chinese visits and close trade relations with Peking, North Korea's Kim Il Sung appears able to act without much Chinese guidance by playing Peking off against the other powerful neighbor, the Soviet Union.

"It is as difficult for the Chinese as for anyone else to tell Kim to do anything or not to do anything," said a diplomat whose country has relations with Pyongyang. "The Chinese have more economic leverage than the Soviet Union, with their heavy oil shipments, but I have the impression Kim Il Sung wants to stay aloof from both powers and does just what he thinks will help him."

At ceremonial occasions, the Chinese reaffirm their support for Pyongyang's efforts to reunify the peninsula and expel all U.S. troops from the South. The Chinese appear strangely reluctant, however, to go much further than that. When Pyongyang denounces Seoul, the Chinese official press usually only reports the North Korean statement and rarely issues a denunciation of its own.

A New China News Agency dispatch Sunday said, for instance, "The Korean Central News Agency was authorized to issue a statement yesterday to expose the South Korean authorities' fabrication of "southward infiltration." The Chinese agency story then went on to quote some parts of the statement, carefully attributing each part to the North Koreans.

Both publicly and in private conversations with American visitors and diplomats, the Chinese endorse Kim's effort to remove U.S. troops peacefully from South Korea. But when Americans press the point, arguing that it is inconsistent for the Chinese at the same time to support continued U.S. military power to counter the Soviets in other unstable parts of the world, the answers are often vague and unresponsive.

When asked recently whether he thought it was a good idea for the United States to decide not to withdraw more troops from Korea, a top Chinese Foreign Ministry official replied, "I think you should talk to the North Koreans."

"I don't think the Chinese are unhappy at all about the U.S. troops in Korea," said one non-aligned diplomat here. "They know how close the Russians are there."

Diplomats here say they are as puzzled as anyone by the recent apparent twists in North Korean activities, seeking talks while at the same time engaging in border conflicts. They usually rule out any struggle within Korea between factions aligned with China, the Soviet Union or other powers.

The apparent plan to bring Kim's son, Kim Chong Il, into new power in the government is thought to have a bearing on all the elder Kim's actions. Analysts here say it is difficult to interpret the Kim strategy, but that it may be aimed at weakening the South Korean government by suggesting unification and blaming Seoul for any failure to rejoin the divided state.

Peking emphasizes the need for a peaceful solution to the problem of a divided Korea and assures listeners that North Korea is no threat to that peace. The Chinese do not appear to have forgotten the Korean War, when Stalin apparently encouraged Kim to attack the South and left the Chinese in a position where they eventually had to enter the war. They have assiduously courted Kim ever since, and would likely husband whatever influence they have with him until that day when they think his actions might again draw them into war.

Chinese Communist Party Chairman Hua Guofeng visited North Korea in 1977 underlining Pyongyang's special status by pointing out that it was his first visit abroad. A visit by Vice Premier Deng Xiaoping, probably China's leading policy-maker, folowed.

Kim visited China in 1975, but has not visited the Soviet Union since 1961. Soviet visitors to Pyongyang have been not nearly as prominent as Cinese visitors. Kim has hosted Prince Norodom Shihanouk and gave oral support to the Khmer Rouge in Cambodia against the Soviet-backed Heng Samrin forces.