A divided Alexandria City Council, restricting the powers of its own Human Rights Commission, yesterday upheld a controversial ban on the sale of beer and wine to customers under 21 in Old Town bars and restaurants.

The decision, which opponents claimed raises fears of age discrimination and possible racial bias, left intact the voluntary ban imposed last year by bar and restaurant owners in an attempt to curb alleged rowdyism in the city's historic district.

Under the change, the human rights agency still will be empowered to hear complaints from youthful patrons, but on sharply narrowed grounds. Those include whether establishments clearly post signs warning of the policy and apply it uniformly.

"They can't pick and choose who to sell to," said Vice Mayor Robert L. Clahoun.

The decision was prompted by the agency's finding that a 19-year-old woman's rights were violated last September when an Old Town nightspot -- The Warehouse -- refused to sell her beer. Virginia law says anyone 18 or over may purchase beer legally.

"In our opinion they will allowing these restaurants to break state laws," Alexandria Human Rights Administrator Steve Levinson said before the City council vote. "We don't want any group excluded from our jurisdiction."

Councilman Nelson E. Greene Jr., the council's only black member, agreed, saying he could never support the amendment.

"What will prevent you, if you have trouble with blacks, from barring me?" he asked. "I haven't seen anything in the report that shows the 18-to-21 age group has caused all these problems."

But restaurant owners argued in support of the ban. "I'm pleased to report that the [ban] has been extremely successful," Bruce Betzel, an owner of The Warehouse, told the council. "If that [Human Rights ruling] had been shoved down our throats, you would have the same situation on lower King Street that you have a few years ago."

Fourteen restaurants and bars, most of them near the city's waterfront joined in the voluntary ban when it was begun last July. Betzel said yesterday only one restaurant on lower King Street, the Fish Market, does not participate in the arrangement.