Canadian television regulators ordered the publicly owned Canadian Broadcasting Corp. today to stop showing popular American movies during prime time, reduce its broadcasts of National Hockey League games and other professional sports and devote more programming to regional cultural issues and news.

The CBC immediately rejected the demands as fiscally irresponsible, saying sports and movies provide a large part of the advertising money it uses to subsidize home-grown programming.

The confrontation, which has been simmering for nearly a year, broke into the open today as the Canadian Radio-Television and Telecommunications Commission extended the licenses of the CBC's network of radio and television stations for another seven years. But, for the first time, it set conditions that CBC officials said they might appeal to the federal cabinet, or simply ignore.

"There is no way the CBC can implement these decisions," said Richard Rabinovitch, who took over the helm of the troubled public broadcaster only two months ago. "They want us to do more with less."

Rabinovitch said that cutting foreign movies from its prime-time schedule would take $35 million a year from the CBC's $500 million budget while other requirements imposed by the regulators would require at least $100 million in new spending.

But commission chairman Francoise Bertrand, who, like Rabinovitch, was appointed by Prime Minister Jean Chretien, said the CBC could accommodate the licensing conditions by "reallocating resources" and tapping into Canadians' creative energies to produce programs that their countrymen will want to watch.

In its order, the commission waded into two political thickets, one involving public vs. private broadcasting, the other involving the protection of Canadian culture.

Over the last decade, two private television networks have emerged in Canada to compete with the CBC for programming and advertising revenue in English-speaking Canada. Executives of these networks complain that when bidding for the rights to blockbuster American movies or professional sports events, they should not have to compete against the CBC, which gets 75 percent of its funds from the federal treasury. In its ruling, the commission effectively sided with the argument that the CBC should stick to doing things that private networks either can't or won't do.

Ironically, the CBC is already the biggest producer of home-grown television shows. While the private networks exist largely to rebroadcast American shows, 90 percent of CBC programs are produced in Canada.

But CBC executives say that many of those home-grown shows have trouble breaking even as viewers gravitate to American shows offered not only on private networks, but through cable feeds from nearby American cities, such as Buffalo, Detroit and Seattle. To be able to maintain and expand Canadian production, CBC officials argue that they need the revenue from professional sports and an occasional American movie special.

Professional sports--including "Hockey Night in Canada," a double-header that is a fixture in the Saturday nights of millions of Canadians--now take up an average of 25 percent of the CBC's prime-time schedule.

The CBC's mission and future have been the subject of active debate in Canada for the past five years, ever since the Chretien government cut its public funding by $250 million a year. Rabinovitch said today that the commission seems to think the CBC should become more like the U.S. Public Broadcasting System, which focuses on "elite" programming shunned by the commercial networks. He said he thinks Canadians want a more vibrant public broadcaster that appeals to all viewers.