WASHINGTON (AP) _ The Federal Communications Commission on Thursday approved the sale of nine of Metromedia Broadcasting Corp.'s major-market radio stations.

The stations will be purchased in a leveraged buyout by the managers of the stations, organized as Metropolitan Broadcasting Corp.

In a leveraged buyout, a company or its units are acquired largely through borrowed funds that are repaid through sale of the target company's assets or profits.

The commission, in making the decision, signaled a review of its cross- interest policy that prohibits an individual from having either ownership or managerial interests in more than one station in a market.

Metromedia, which is in the process of liquidating itself, retains ownership of WCBM-AM in Baltimore, a long-distance telephone company and some cellular telephone and paging concerns.

Last week, holders of warrants to buy future Metromedia securities were offered a chance to sell their holdings back to the company as part of the self-liquidation.

Metromedia's long-time president and board chairman John Kluge already controls more than 95 percent of the company, which he acquired in his own leveraged buyout.

The radio sale includes: KRLD-AM, Dallas; WIP-AM and WMMR-FM in Philadelphia; WNEW AM and FM, New York; KMET, Los Angeles; WASH-FM, Washington; WOMC-FM, Detroit and WWBA-FM, St. Petersburg, Fla.

Morgan Stanley Leveraged Equity Fund, L.P. was given approval to purchase 20 percent equity interest in Metropolitan when closing on the sale by Metromedia takes place.

Although the Fund also owns a share of Emmis Broadcasting Corp., which also holds licenses in Los Angeles, New York, and Washington, the FCC ruled that it held such a small portion of each that it could not control either company.

In a letter to Metromedia and Metropolitan, the commission noted it would soon begin assessing whether there is any need for its cross-interest policy, which allows an owner to hold ownership or managerial interest in only one station in a market, but warned that its finding of no cross-interest violation in this case did not indicate a predetermination of the cross- interests policy question.

The cross interest rule says a person or corporation cannot hold even a passive interest in one station while maintaining an ownership or managerial position at another station. For example, a major stockholder of a TV station may not be the general manager of a cross-town rival TV station.

The commission noted that substantial changes have occured since 1949, when the cross-interest topic was last reviewed.

''The competitive nature of the broadcast marketplace has evolved far beyond the situation that pertained over 35 years ago,'' the commission said.

''Moreover, multiple ownership and attribution rules have been adopted and modified, and numerous rules and policies that police private business practices have been eliminated.''