Attorney General Eric Holder says the Justice Department is reviewing complaints about surveillance by the NYPD of Muslim and Arab communities.
At a hearing before a House appropriations subcommittee, the attorney general said the department has not opened a formal investigation.
The Associated Press first reported that the NYPD compiled lists of mosques and Muslim businesses it saw as potential security risks for reasons that included endorsing conservative religious views or having devout customers.
The AP found that NYPD has dispatched teams of undercover officers into minority neighborhoods as part of a human mapping program and has monitored daily life in bookstores, bars, cafes and nightclubs.
Police have also used informants known as mosque crawlers to monitor sermons even when there's no evidence of wrongdoing.