The most senior intelligence chief in the New York police department wanted a source in every mosque "within a 250-mile radius" of the city, according to the latest in a series of revelations about NYPD-led surveillance of Muslims across north-eastern America.

The latest disclosures, by the Associated Press, reveal the ambitions of an effort led by David Cohen, a former CIA officer who went on to become the NYPD's deputy commissioner for intelligence.

"Take a big net, throw it out, catch as many fish as you can and see what we get," one investigator, quoted by the AP, recalled Cohen saying.

Officials cited by the AP said they never managed to reach the goal of having sources in every mosque within 250 miles. But documents obtained by the news agency show the NYPD successfully placed informants or undercover agents – sometimes both – into mosques from Westchester County to New Jersey.

Civil rights campaigners have told the Guardian that the surveillance program violated even the last vestiges of restrictions placed upon the NYPD in the wake of controversial police infiltration of activist groups in the 1960s and 1970s.

In an attempt to push back at the latest revelations, senior NYPD officers held a press briefing on Thursday to deny any wrongdoing. Paul Browne, the deputy commissioner for public information, said: "There's been a suggestion that what we are doing doesn't comport with legal requirements, and that's not the case. Everything we're doing is done constitutionally."

Thursday's disclosures came in the latest of a series of reports by the AP into the NYPD's monitoring of the Muslim community, which extended far beyond the city boundaries.

Over the weekend it was revealed that the New York police department had conducted surveillance at more than a dozen universities throughout the north-eastern United States, resulting in severe criticism from numerous college officials and some of the students who were monitored.

No evidence has emerged of wrongdoing on the part of the students that were monitored.

On Wednesday the AP disclosed that the department had also conducted extensive surveillance efforts in New Jersey's largest city, Newark, for months during 2007. According to a 60-page police report, officers with the department's demographics unit mapped and photographed 16 mosques, labelling them "Islamic religious institutions." Numerous restaurants are also profiled in the report, including a branch of Dunkin' Donuts.

The AP said the documents it had obtained showed what the NYPD's informants – known informally as "mosque crawlers" – gleaned from inside the houses of worship.

The NYPD used these sources to get a sense of what worshippers felt whenever an event generated headlines. The goal, former officials told the AP, was to alert police to potential problems before they arose.

Newark mayor Cory Booker claimed he was unaware of the program and never would have allowed it if the focus was solely on citizens' religious affiliations.

New Jersey governor Chris Christie, who was the state's federal prosecutor in 2007, also says he unaware of the program. He described the operation as "disturbing" and launched an investigation.

The NYPD has defended its intelligence-gathering operations, arguing that it only follows leads about suspected criminal activity. While critics say the department's programmes lack transparency and oversight, the NYPD says it follows the same rules as the FBI. It also said on Thursday that it had informed New Jersey authorities about what it was doing.

The latest AP report suggests the department may have systematically violated restrictions on its right to record the conversations of private citizens. The steadily-growing controversy surrounding the department's surveillance of Muslim communities is rooted in an ongoing court battle dating back to the 1970s.

The Handschu agreement, as it is often referred to, was established in 1985 after decades of covert NYPD infiltration of activist groups including the New York City chapter of the Black Panthers. It also kept tabs on citizens who had done nothing more than sign a petition to end the Vietnam war, reporting their political positions to potential employers.

The element of the NYPD responsible for this surveillance went through a number of names, including the Italian squad, the black hand squad, and the bureau of special services. Today it is known as the intelligence division.

Handschu restricted the department's powers to monitor political groups, stipulating that police needed information indicating that a crime was being committed in order to investigate political activity. The rules remained in place for over 15 years.

In 2002 the NYPD, under the guidance of former CIA officer Cohen, lobbied to have Handschu's restrictions significantly loosened, following the September 11 attacks of the previous year. The department argued that it could not effectively fight terrorism with the rules in place.

The NYPD largely got what it wanted in 2003, when significant modifications were made to the agreement.

Civil rights attorney Jethro Eisentstein, who is involved in a class action lawsuit against the NYPD in relation to Handshu, says what remains of the agreement is vitally important to the latest revelations concerning the NYPD's surveillance of Muslim communities.

"What was left and what we are currently in court about, is a restriction that said the police department had the right to attend public meetings on the same terms of the public, generally," Eisenstein explained. "But they could not maintain records of what they learned at such meetings unless it related to terrorism or criminal activity."

The restriction not only remained after the revision of Handschu; it carries the force of the law. "It is still binding on them. It is a rule enforceable in court," Eisenstein told the Guardian.

According to a 2006 police report obtained by the AP (PDF), undercover NYPD officers with the intelligence division recorded the names and comments of well-over a dozen Muslims speaking at mosques and Islamic centers around New York City. The topic of conversation was a Danish newspaper publishing inflammatory cartoons of the prophet Muhammad in September, 2005.

The Muslim community members, who are identified in the report by name, repeatedly repeatedly condemn the cartoons and call for various protests and demonstrations. The comments that were recorded appear to fall well within the individuals' constitutional rights to free speech. Again and again the individuals denounce violence and call for peaceful responses.

As the AP notes, the closest an observed individual comes to referencing violence is in his use of the word "inqilab", which means to change the political system and, depending on the context, can be call for peaceful reform or a coup-style upheaval. The undercover officer translated the word to mean "fight".

Eisenstein says the undercover officer's report on the discussion is "a clear violation" of the Handschu restriction. The cover of the report reads "Distribution: Commissioner", suggesting it was intended for NYPD commissioner Ray Kelly's personal review.

"This is a series of recorded statements and, if you look at them, they're all totally protected by the first amendment," Eisenstein pointed out. "They're people saying we should protest what should be done but we should not engage in violent activity."

"This is exactly what they're not supposed to do," he added.

Eisenstein underscored the centrality of Hanschu in holding the department accountable: "It is the one existing set of restrictions on the New York City police department as they go about this widespread programme of surveilling people because they're Muslim."

At the NYPD press briefing on Thursday, Peter Farrell, senior counsel of the city's law department, said the city's surveillance programs were legal. "There is no constitutional prohibition against a police department collecting information. What's unconstitutional is if they then use that information to chill someone's first amendment rights or to impose harm on them."