PHILADELPHIA (AP) _ A television anchor filed a sex- and age-bias complaint against CBS, alleging the network illegally discriminated against her when it replaced her with a younger woman.

In a brief filed Friday with the federal Equal Employment Opportunity Commission, Diane Allen said CBS, owner of Philadelphia affiliate WCAU, Channel 10, unfairly demoted her from co-anchor of the 11 p.m. newscast.

Allen, 44, was replaced in March by anchor-reporter Jane Robelot, 31. Allen still co-anchors the 5:30 p.m. newscast. Robelot and Larry Kane, 49, are co- anchors at 6 p.m.

Allen isn't seeking damages or any specific action from the station, said her attorney, Harold Goodman. Her main goal is ''to identify what we believe is systematic age and gender discrimination against women over 40,'' Goodman said.

Allen could take CBS to court over the allegations, however, he said.

''There's no doubt in my mind that I've been discriminated against,'' Allen said.

''Somebody has to stand up and say, 'You can't do this. It's immoral and illegal.' I know there could be retribution,'' she said, ''and that I could be blackballed, but I feel that management has already crushed my career.''

Allen's three-year contract expired in February and she worked without a contract until last month, when she signed a two-year extension.

She said she did so because ''management implied that if I didn't sign they would fire me'' and that the new agreement pays less than half her former salary, which has been estimated at $500,000 a year.

Her complaint of sex discrimination stems from public remarks March 21 by WCAU general manager Gene Lothery that Robelot ''makes (Kane) better'' at 11 p.m. ''He's a strong anchor. She softens him.''

Allen labeled the comment ''sexist.''

Calls seeking comment early today from Lothery and Robelot were not immediately returned.

A news celebrity in Philadelphia, Allen made headlines in 1988 when she left NBC affiliate KYW-TV for the CBS station.