The NYPD has had a stellar track record of protecting the city from another 9/11, foiling more than 20 planned terrorist attacks since 2001. But some worry the department is losing its terror-fighting edge as it tries to please Muslim grievance groups.

Last year, for instance, it censored an anti-terror handbook to appease offended Muslims, even though it has accurately predicted radicalization patterns in recent “homegrown” terror cases. Rank-and-file NYPD officers, detectives and even intelligence and counterterrorism units are officially barred now from referring to the handbook or the scientific study on which it was based.

Former law-enforcement officials fear its removal as a training tool may be hurting efforts to prevent terrorist activity, such as the vehicle-ramming attacks plaguing European cities.

“The report was extremely accurate on how the radicalization process works and what indicators to look for,” said Patrick Dunleavy, former deputy inspector general of the New York state prisons’ criminal-intelligence division, who also worked with the NYPD’s intelligence division for several years.