A long-debated experiment to distribute free, clean needles to 200 drug addicts in an effort to slow the spread of AIDS has been judged legal and will begin soon, the city's health commissioner said.

Dr. Stephen C. Joseph said in an interview published in the New York Times that the experiment is expected to begin in about 10 weeks.Needles are already distributed in several other countries. But despite nationwide debate, no government agency has yet done so in the United States.

If New York's start-up program is successful, officials hope to broaden the distribution among the city's estimated 200,000 intravenous drug-abusers. Sample blood tests indicate about half that group are already infected with the AIDS virus.

The experiment was approved this week by the state Health Department and local prosecutors have judged it to be legal, the Times said.