A lengthy Canton wall poster, apparently produced with some Communist Party backing has made the most direct attack observed yet on Chinese economic policy and has demanded rapid introduction of foreign technology and management practices.

The poster, character by character and brought here by a traveling Japanese diplomat, goes so far as to compare Chinese economic development unfavorably with Japan's yet it has been allowed to remain prominently displayed along the Canton waterfront for at least a week, drawing much attention.

"In 1957," the poster said, "Japan produced about 10 million tons of steel, approximately the same amount as China. But in 1972, Japan's steel production was more than 100 million tons while ours was only 20 million tons . . . Does this mean the Chinese people are less intelligent than the Japanese, that we are less diligent? Does it mean that Chinese natural resources are inferior to those of Japan or that our social system is somehow lacking?"

No, the poster concluded, but the Chinese system needs major changes. It proposed a nine-point program including wage increases and expanded fringe benefits, more production of consumer goods and "rapid introduction of foreign technology."

"We have satellites in the sky," the poster said, "but our peasants are still working with shoulders-poles. We should not continue this forever."

The poster, first reported by the Far Eastern Economic Review and confirmed by other sources here, is signed by "Kung Jen," apparently a pseudonym based on pun for the word for "workers." Its prominence and the fact that it cites domestic and foreign production figures usually available only to high-ranking party officials suggests that t is a trial balloon launched by some provincial, or even higher-level, leaders.

The poster said that Japan, which "suffered great losses in World War II," still manages to produce almost twice as many motor vehicles as China and has a 60 per cent higher yield per acre in rice farming.

To close gap, the poster argued, Chinese workers need more incentives. All wages should go up and in the future salaries should be pegged to each worker's output. The poster said social welfare benefits ought to be expanded, particularly for workers who lose their jobs. This contradicts to the official claim that there is no unemployment in China.

More consumer goods, such as bicycles, radios and sewing machines, should be produced and working conditions, particularly in rural areas, should be improved. "We should not develop agriculture solely on the basis of collective accumulation and hard work, "the poster said.

Since the purge of Mao Tse-tung's widow, Chiang Ching, and other so-called radical Peking leaders in October, the official Chinese press has hinted at plans for wage increases and other economic policy changes. But the Canton poster, which blames Chiang and her "gang of four" for China's economic ills, provides the boldest assault to date on the Maoist economic doctrine that workers should be motivated solely by political fervor and class loyalty, not by more money.

New Communist Party Chairman Hua Kuo-feng is presiding over an industrial plant still recovering from the labor strikes, political squabbles and earthquakes of the past year. An overall wage increase now might severely hinder new economic growth and new equipment purchases. Hua's propagandists have cautioned that salary increases must be tied to increases in production.