NEW YORK : The New York Police Department (NYPD) routinely broke rules in investigations of Muslim groups, including failing to explain its use of undercovers and informants, the department’s watchdog said in a report.

In terror probes as far back as 2004, the Office of the Inspector Generalfor the NYPD found  that police has repeatedly failed to get permission to continue investigations of Islamic groups. Under the long-standing terms of a class action suit settlement, the NYPD’s Intelligence Bureau is supposed to get permission to continue probes of political activity within specified time limits, but didn’t bother more than half the time, the report found.

 This failure resulted “in investigations of political activity that continued without the requisite authorization,” the report states.

The report was intended to measure NYPD’s compliance with a longstanding set of rules , known as the “Handschu” guidelines, first imposed on the department decades ago as part of a federal court settlement. However, the regulations were relaxed following the 9/11 attacks to allow police to expand counter-terrorism and intelligence efforts.

“These failures cannot be dismissed or minimized as paperwork or administrative errors,” the report said. “The very reason these rules were established was to mandate rigorous internal controls to ensure that investigations of political activity - which allow NYPD to intrude into the public and private aspects of people’s lives - were limited in time and scope and to ensure that constitutional rights were not threatened.”

 More than 95% of the individuals under investigation in these cases were “associated with Muslims and/or engaged in political activity that those individuals associated with Islam,” the report found.

 Inspector General Philip Eure found the NYPD failed half the time to provide by required deadlines justification for continuing them.

Earlier this year, New York city agreed to settle a lawsuit that claimed a secretive NYPD spying programme that conducted broad surveillance of Muslim neighborhoods, mosques and businesses violated the Handschu guidelines. The unit that conducted the surveillance was dismantled in 2014 after Mayor Bill de Blasio took office.

The Associated Press, the American news agency,  first revealed in 2011 that the NYPD was spying on Muslims in the states of New York and New Jersey, showing that the department investigated countless innocent Muslims and put information about them in secret police files.

Donna Lieberman, executive director of the New York Civil Liberties Union, said in a statement that her group stood by its “allegations that there were often no valid reasons for the NYPD to open or extend investigations of American Muslims .

“The inspector general’s report has provided yet more evidence that the NYPD’s surveillance of American Muslims was highly irregular, operated in a black box and violated even the weaker rules that existed before our proposed settlement,” Lieberman said.