The City Council has permanently adopted a controversial loitering law that police say has been instrumental in increasing drug arrests in troubled areas of the city.

The law, which allows police to arrest a person suspected of loitering to buy or sell drugs, was adopted last March on an experimental basis, Police Chief Joseph A. Santoro said. He said he has met with community leaders and ministers to assuage concerns that the law is unconstitutional and discriminatory against blacks. There was no public opposition to the council's unanimous action Tuesday.

The law has has resulted in five arrests. In two cases the charge was upgraded to felony sale of cocaine and in a third to possession of marijuana. The other two people who were arrested pleaded guilty to the loitering charge and were fined $705 and given three years' probation, Santoro said. The council asked him to report every six months on how the law is working.