A federal prosecutor today implicated the chairman of Warner Communication Inc., the world's biggest entertainment conglomerate, in an alleged scheme to create a cash bribe fund for acquiring stock in another business.

The sensational allegation against Steven Ross, Warner's chairman and guiding force, was made by Assistant U.S. Attorney Nick Ackerman in opening remarks at the jury trial of another Warner official, former assistant treasurer Solomon Weiss.

Ackerman told the jurors at U.S. District Court here, "You will learn how the chairman of the board of Warner designated the defendant Weiss as banker or overseer of a secret cash fund at Warner."

Ross has not been charged in the case. Martin Payson, Warner's general counsel, issued the following statement in response to the prosecutor's remarks: Ross "unequivocally denies any authorization or participation or knowledge of any secret cash fund."

Weiss was indicted for allegedly accepting bribes in return for getting his company, Warner, to buy stock in Westchester Premier Theatre in Tarrytown, N.Y.

Several top Mafia figures, including the late Carlo Gambino, have been tied by federal investigators to the now-defunct 3,500-seat theater. The theater, which declared bankruptcy in 1978, had featured big name performers such as Frank Sinatra, Dean Martin and Steve Lawrence and Eydie Gorme.

On Feb. 10, 1981, Jay Emmett, one of three presidents who ran Warner under Ross, pleaded guilty to interstate transportation of stolen funds in connection with the Westchester theater case. He is expected to testify for the government in the Weiss case.

Another former Warner executive, Leonard Horwitz, who also was vice president of the Westchester theater, pleaded guilty to tax evasion in connection with the case. He had his 3-year sentence reduced to 9 months for agreeing to cooperate with the government.

In his remarks, prosecutor Ackerman alleged that in 1973 Weiss "on behalf of Warner" accepted $170,000 in cash bribes from a theater representative. In return, Weiss allegedly arranged for Warner to purchase 40,000 shares of stock in the publicly-owned theater.

"Emmett met with Steven Ross," Ackerman alleged, "who instructed Emmett to bring Horowitz together with Weiss."

But Weiss' attorney, Robert Kasanoff, told the jurors that the two government witnesses, Emmett and Horowitz, were "lying to save their own skins."