HONG KONG, Dec. 18— Peking said today that the Indian occupation of Dacca represented “annexing East Pakistan with armed forces.”

In a dispatch from the Chinese capital, Hsinhua, the Chinese press agency, said that after taking over Dacca “the Indian aggressor troops will hang on in East Pakistan and impose military occupation there.”

The dispatch, dated Dec. 17, a day after the Indian capture of Dacca, said nothing about the surrender of the city's Pakistani de fenders.