NEW YORK - Outraged Muslim students are calling for an investigation into the New York Police Department’s surveillance of Muslim college groups, but the city’s mayor, Michael Bloomberg, defended the intelligence gathering as a justifiable counterterrorism tactic.

There is renewed controversy over the practice since it was reported over the weekend that the NYPD monitored Muslim student groups at colleges, including the University of Buffalo, the University of Pennsylvania and Yale University.

The NYPD also monitored daily websites of Muslim student organisations at New York University, Syracuse University, State University of New York campuses, Columbia University, Queens College, Baruch College, Brooklyn College and LaGuardia Community College.

In one instance, the department reportedly sent an undercover agent on a white-water rafting trip with some Muslim students from the City College. The undercover officer recorded students’ names and noted in police intelligence files how many times they prayed during the trip, even though they had not been accused of any wrongdoing.

“I can’t trust anybody, I don’t know who around me is doing what,” said Jawad Rasul, a Pakistani-American student of City College who was on that rafting trip. “What we have seen in many cases is that a lot of these undercover agents, they were not just simply watching. Anytime they saw that someone had a habit of talking, of being outspoken, they started instigating things and that takes this spying to a whole different level.”

On Tuesday, City College officials released a statement that said in part, “Absent specific evidence linking a member of the City College community to criminal activity, we do not condone this kind of investigation.”

“It kind of is a slap on the face as we are trying to assimilate into the country,” said Rasul.

“This tactic actually creates more hatred. A better approach would be to take a proactive approach and engage the Muslim youth at a large level.”

The Association of Muslim American Lawyers also sent a letter to State Attorney General Eric Schneiderman, urging him to investigate what it calls violations of Muslims’ civil rights by the NYPD.

The Yale president also issued a strong statement against the surveillance of its students, calling it antithetical to the varsity’s values.

Addressing reporters in an unrelated Brooklyn event, Bloomberg justified the NYPD investigations, saying 12 people arrested or convicted on terrorism charges had once been members of Muslim student associations, adding that the student groups’ websites were in the ‘public domain’.

“We have to keep this country safe. This is a dangerous country,” said the mayor. “It’s very cute to go and to blame everybody, to say we should stay away from anything that smacks of intelligence gathering. The job of our law enforcement is to make sure that they prevent things and you only do that to by being proactive. You have to respect people’s right to privacy; you have to obey the law.”

The student monitoring was part of a much larger intelligence-gathering operation on Muslims by the NYPD that has come under fire by civil liberties groups and nearly three dozen members of Congress.

The Muslim Students Association of the University at Buffalo said it felt discriminated against by the secret investigation conducted by a police agency 400 miles away.

The NYPD built databases showing where Muslims lived, worked, shopped and prayed. Plainclothes officers known as rakers eavesdropped in cafes, and informants known as mosque crawlers reported on weekly sermons.

Defenders of those efforts say police investigators needed to understand the community to spot potential plots.