James Packer's casino giant Crown Resorts has suffered a steep drop in spending by wealthy high-roller gamblers coming from China, as the Chinese economy grinds to its slowest growth in nearly three decades.

"Chinese people, like Australian people, are suddenly feeling a bit poorer than they were a couple of years ago," Crown's executive chairman, John Alexander, said on Wednesday. "It all goes to spending patterns."

James Packer is Crown's largest shareholder. Credit:AAP

Worldwide, gambling operators have been gripped by growing uncertainty about the fortunes of their lucrative international high-roller programs, where mainly Chinese punters, who often play baccarat, can turn over hundreds of thousands of dollars a hand and millions of dollars an hour.

Softening economic growth in China, the government's crackdown on conspicuous consumption and simmering trade tensions with the United States have fuelled fears of a possible pullback in volumes of wealthy Chinese gamblers visiting Australia, and a downturn in VIP revenue on which casino operators have become increasingly reliant.