New York will appoint an independent monitor to review counter-terror police investigations as part of reforms designed to protect Muslims from discriminatory and blanket surveillance, officials said Thursday.

Civil liberty campaigners welcomed the changes, which settle two lawsuits, saying the move by the country's largest police force sent a powerful message at a time of rising anti-Islamic sentiment.

The lawsuits alleged that New York police stigmatized communities based solely on religion, and that lawful political and religious activities were subject to unwarranted police surveillance following the 9/11 attacks.

The terms of the settlement, which were reached after more than a year of negotiations, must be approved by a federal judge.

The American Civil Liberties Union, which helped bring one of the suits, welcomed what it called a "watershed."

Discriminatory surveillance sowed fear and mistrust, drove down mosque attendance and forced religious leaders to censor conversations out of concern that they might be misunderstood, the group said.

Hina Shamsi, ACLU National Security Project director, said it introduced "much-needed constraints on law enforcement's discriminatory and unjustified surveillance of Muslims."

"At a time of rampant anti-Muslim hysteria and prejudice nationwide, this agreement with the country’s largest police force sends a forceful message that bias-based policing is unlawful, harmful and unnecessary," she added.

Muslim community leaders have complained of an unprecedented backlash across the United States after extremist attacks in Paris and San Bernardino, fueled by rhetoric on the presidential campaign trail.

The new representative, an independent lawyer, would have the power to ensure all safeguards are followed and serve as a check on investigations directed at political and religious activities, ACLU said.

They must report any violations to the police commissioner, who must investigate and report back, it added.

The reforms will also limit police use of undercover and confidential informants, and end open-ended investigations by imposing time limits and require status reviews every six months, ACLU said.


Rebuild relations

Police will now need facts alleging possible criminal activity before opening an investigation, the ACLU said.

The police denied the proposed settlement would weaken their ability to investigate and prevent terror activity. Mayor Bill de Blasio and police commissioner Bill Bratton welcomed the terms.

"This settlement represents another important step toward building our relationship with the Muslim community," said de Blasio.

"The modifications also bring the guidelines closer in line with FBI practices, which is helpful in working collaboratively with our federal partners," said Bratton.

Deputy police commissioner of intelligence and counterterrorism, John Miller, will retain "sole authority" over all intelligence investigations and decisions, the police department said.

The mayor will appoint the independent monitor in consultation with the police commissioner.

"This additional voice will increase transparency while maintaining the confidentiality of investigations," the police department said.

In April 2014, police announced the disbanding of the Demographics Unit, a deeply controversial and heavily criticized group that sent undercover officers to spy on local Muslims.

New York Muslims had challenged the spy program, arguing it stigmatized hundreds of thousands of innocent people.

The ACLU said that after 9/11, police officers monitored entire communities and sent paid infiltrators into mosques, student associations and community events, including a wedding, to take photos and keep tabs on Muslims.

The Pew Research Center estimates that about 3.3 million Muslims were living in the United States in 2015. New York and the neighboring state of New Jersey are among the biggest communities.