BEIJING, DEC. 24 -- China's Communist Party leadership has decided to close the party's leading theoretical journal, Red Flag, a move that is certain to offend some of the country's orthodox Marxists, a usually reliable Hong Kong newspaper reported.

The procommunist newspaper Wen Wei Po reported today that the decision to shut down the 48-page theoretical magazine was made by "the highest leadership of the Chinese Communist Party." Observers said this indicated that Communist Party chief Zhao Ziyang had made the decision to close the 29-year-old publication.

Published twice a month, Red Flag was once a bastion of "leftists," but later featured the writing of "conservatives" who questioned the pragmatic, reformist economic policies initiated by Zhao Ziyang and his mentor, senior leader Deng Xiaoping.

In recent issues, however, Red Flag supported the government's reforms.

Zhao and other leaders have apparently been complaining recently that the country's theoreticians and ideologists have lagged behind practical developments instead of taking the lead in formulating new ideas that have practical impact.

It was disclosed last month that in January a new magazine called Reform will be published to serve as a forum for specialists from both theoretical and practical fields.

Meanwhile, a staff member at the Red Flag offices here said he could not confirm that the magazine was being closed. Long Wenshan, a spokesman for the government's press and publications bureau, said his bureau had no information about plans to close Red Flag.

But the Hong Kong newspaper, Wen Wei Po, which is usually well informed about press and propaganda matters in China and often reports developments in this field ahead of other publications, was widely believed to be accurate in its report. Red Flag's editor-in-chief, Xiong Fu, resigned several months ago, and rumors then began to circulate that the magazine would be shut down.

Red Flag was a favorite magazine of the late party chairman Mao Tsetung. Its name is written on the masthead in Mao's calligraphy.

First published in June, 1958, Red Flag had a circulation of 3.5 million as of 1983. As the mouthpiece of the Communist Party's Central Committee, the publication served as a key instrument of the "gang of four" leaders who dominated Chinese politics during the Cultural Revolution years.

In an interview published here last month, Jiang Yiwei, who will be chief editor of the new magazine Reform, took a slap at theoreticians who have failed to test their theories and put them into practice.

Jiang said that some pragmatists now find little of value in theoretical work. "They think that theoreticians are nothing more than troublemakers," said Jiang.