LOS ANGELES (AP) _ The U.S. Commission on Civil Rights, prompted by complaints of racism and sexism in the newsrooms of two network-owned television stations, will investigate all major local TV stations.

KCBS-TV Channel 2 and KNBC-TV Channel 4 have been accused by workers and civil rights groups of giving preferential treatment to white male employees; KCBS also was accused of unfair coverage of minority communities.

Philip Montez, the commission's western regional director, said the probe was largely prompted by a formal complaint filed Tuesday by City Councilman Richard Alatorre.

''I don't know what we'll find in this investigation, but there is a lot in the air,'' Montez said. ''The best thing to do at this point is to look at all the channels.''

KNBC-TV disputed the allegations.

''KNBC-TV has had a longstanding policy that we are an equal opportunity employer. The station has a strong commitment to this policy,'' KNBC-TV spokeswoman Regina Miyamoto said Thursday.

Alatorre's complaint alleges a ''systematic effort to deny equal treatment to Latinos, other ethnic minorities, women and the gay community employed in the broadcasting industry.''

He singled out the CBS station in his complaint, saying he had ''received information on KCBS that describes working conditions that are unacceptable.''

He declined to give specific information about what he had been told by employees, saying he wanted to protect the confidentiality of those still working at KCBS.

But Alatorre wrote that ''Latinos and other minorities should not be subjugated to constant harassment and intimidation, demotions and indiscriminate and disproportionate firings and-or terminations.''

Leaders of the Los Angeles Urban League, the Gay and Lesbian Alliance Against Defamation-L.A. and the National Hispanic Media Coalition also said they have heard numerous recent complaints from KCBS employees.

Insensitive racial remarks by management, favored treatment of white male reporters, lack of promotion for minorities and negative coverage of ethnic communities were among the claims made.

KCBS General Manager William Applegate denied the allegations by Alatorre and others and said he had received no complaints.

''KCBS has an excellent record of hiring minorities and, to the best of my knowledge, no minority has been demoted or harassed,'' Applegate said Wednesday.

In addition to KCBS and KNBC, the commission investigation will include KTLA-TV Channel 5; KABC-TV Channel 7; KCAL-TV Channel 9; KTTV-TV Channel 11 and KCOP-TV Channel 13.

In February, Hispanic journalists alleged that discrimination by KNBC-TV management had contributed to the exit of five Hispanic reporters and anchors in the preceding five months.

Current and former staffers claimed that Hispanic journalists had been consistently pushed into the background by news director Mark Hoffman, while white male reporters received better treatment.

KNBC has denied the accusations, and denied that the abrupt resignation of General Manager Reed Manville on March 12 was connected to the bias claims.

But NBC Television Stations President John Rohrbeck noted there was a perceived problem among the newsroom staff of low morale and other problems that required a change in leadership.

He also announced that the station would be hiring an executive to oversee the hiring and promotion of minorities.

Montez said the Civil Rights Commission may also review whether the Federal Communications Commission is properly monitoring practices at Los Angeles TV stations.

He hopes to reach some conclusions about the extent of the investigation in about two months, Montez said.