A wall poster in Peking yesterday made the first known public and personal attack on the late Chinese leader Mao Tse-tung, raising new questions about the still-influential policies and political leaders of his life.

Diplomatic sources in the Chinese capital said the poster, pasted on a wall alongside the capital's busy Avenue of Eternal Peace, referred to Mao's "mistaken judgment about class struggle."

For the first time the poster linked Mao directly with his wife's "Gang of Four" clique, which has been the target of massive criticism in the last two years in China.

The direct criticism of Mao. If allowed to continue, would raise serious doubts about the position of Chinese Communist Party Chairman Hua Kuo-feng, whom Mao suddenly chose as his successor over several more senior candidates just few months before his death. Hua so far managed to maintain his top position and at least a semblance of unity with more-experienced party officials like Vice Chairman Teng Hsiao-ping, despite obvious differences of opinion.

Diplomatic sources said the poster signed by workers at a Peking garage was put up yesterday morning and was still intact late last night, a sign of a least some official approval for its contents. It appeared at the end of a week in which the official Chinese press made some of its most direct attacks ever on Mao's policies without actually referring to China's great revolutionary leader by name.

One passage of the poster was underlined either by the authors or one of the several passersby who stopped to read it yesterday: "Chairman Mao, because his thinking was metaphysical in the last years of his life and for all kinds of other reasons, supported the Gang of Four in raising their hands to strike down comrade Teng Hsiao-ping."

Teng, an enormously popular figure in China, is a 74-year-old twice-purged party veteran who is now leading a movement to abort many of Mao's most egalitarian policies and rebuild the Chinese economy through worker bonuses, new authority for factory managers and college admissions based on academic merit rather than political reliability.

Although Teng is outranked in the party by Hua, 57, and military leader Yeh Chien-ying, 80, he probably has more influence on Chinese policy than any other individual in China today.

When Teng tried to pursue his pragmatic policies in 1975, dogmatists in the ruling Politboro, including Mao's wife Chiang Ching and some colleagues from Shanghai, actively resisted. Shortly after the January 1976 death of Premier Chou En-lai, whom Teng was expected to succeed, the 5-foot-3 official suddenly disappeared from sight and a national campaign against his education policies began, apparently with Mao's blessing.

In April 1976, Teng was officially removed from all offices in the party and government two days after thousands of Peking residents rioted in Tienanmen Square in support of the memory of Chou and the moderate policies that Teng had tried to pursue.

Hua, who had been a Hunan provincial bureaucrat for most of his career and had only been in Peking since 1971, was confirmed as first vice chairman of the party and premier in an April 7 resolution accompanying the resolution dismissing Teng.

Although many of Mao's policies have come under attack in the official press since shortly after his death, party commentators have taken care to praise him personally and blame all mistakes on his wife and her so-called "Gang of Four." The furthest the official press has been willing to go is to suggest that Mao's policies might have to be changed to meet new conditions. Many quotes from Mao himself supporting that pragmatic attitude have been cited.

Yesterday's poster, however, attacked Mao directly. It said the Gang of Four had used "Mao's mistaken judgement about class struggle and used the situation to lodge an all-out offensive against China's revolutionary cause.

"First they used Mao's hand to strike down the representative of China's proletarian revolution, Comrade Teng Hsiao-peng.

"This is made very clear by the resolution of the party's Central Committee that was proposed by Mao and announced" after the Tienanmen riot.

"After that, they imposed a most violent suppression of the revolutionary cadres and the revolutionary people of the whole country."

The reference to the April 7, 1976, resolution dismissing Teng is the most direct attack ever on the critical decisions of that day. So far the official press has avoided mentioning Mao's earlier verdict on Teng, even after Teng was brought back to power in July 1977, apparently because of the ticklish association between that resolution and the one that named Hua as Mao's successor.

Last week it was officially announced that all those punished for their participation in the Tienanmen demostration had been absolved of all blame and the event was declared to be a revolutionary incident.

Official reports at the time said more than 100 persons were injured during the riots, with some cars overturned and some buildings set afire in what probably was the most remarkable outpouring of spontaneous political sentiment on the part of the Chinese people in the last 30 years.

Hua, who has been very adept at adapting to changing policial whims, appeared to be moving to short-circuit any political problems caused by the association between the suppression of the rioters and his rise to power.

The official People's Daily displayed on its front page yesterday a preface written by Hua to commemorate a new book on poems written by some of the Tienanmen demostrators.

One month after Mao's death, Hua and Yeh joined several of Teng's allies in the government and army to purge Chiang Ching and her allies, who were accused of trying to take over the country. Hua has cooperated with the several rapid domestic changes made by Teng since his return to power, but the new party chairman has expressed concern that some changes in education might create a new, unsocialist elite.