The district attorney of New York City's borough of Manhattan says he will stop prosecuting low-level marijuana cases.

Cyrus Vance said Tuesday his office will decline to prosecute marijuana possession and smoking cases starting Aug. 1. He said there will be a few exceptions.

The move comes after The New York Times reported on the persistent racial gap in marijuana arrests.

The Times reported that blacks in the city are eight times more likely to be arrested on low-level marijuana charges as whites. The report said the difference cannot entirely be attributed to more residents in predominantly black neighborhoods calling police to complain about marijuana.

Mayor Bill de Blasio, a Democrat, said Tuesday that the police department will overhaul its citywide marijuana-arrest policies within the next 30 days.