On Feb. 2, 1962, an FBI agent in Chicago asked his boss for permission to develop some promising "anonymous sources" concerning two controversial organizations with headquarters in a building on the city's near west side.

"...[I]t is recommended," the agent's memo said, "that authority be granted to make contact with these sources on or about Feb 10, 1962, sometime during the period l a.m. to 6 a.m."

the request was sensitive enough to be passed on to Washington, where approval was granted for the "maximum security" operation. The "anonymous sources" were an FBI euphemism for warrantless, surreptitious entries, or "black-bag jobs." The memo surfaced in a Chicago court case that gives one of the clearest indications yet of the extent of the black-bag jobs over the past few decades.

No one seems to know how many such break-ins were conducted over the years in the name of national security or some other alledgedly overriding purpose, such as the fight against organized crime, but it would appear that there were thousands. The FBI now concedes that between roughly 1948 and 1966 its special agents "committed at least 500 black-bag jobs in the Chicago area" alone.

That is more than twice the number the bureau had first acknowledged conducting throughout the entire nation over an even longer period.

The issue has come to the fore again in light of a proposed relaxation of existing restrictions on the FBI and other U.S. intelligence agencies as well as President Reagan's explicit refusal last month to declare people's homes immune from such entries in national security cases.

The admission of the FBI's black-bag jobs in the Chicago area are contained in a proposed stipulation to settle longstanding lawsuits against spywork by the Chicago police and other agencies, including the FBI. The settlement, hammered out by government and plaintiffs' attorneys in the litigation and submitted several months ago, is awaiting U.S. court approval.

Meanwhile, it apppears, FBI officials in Washington are only gradually becoming aware of the extent of the practice during the J. Edgar Hoover era.

According to the FBI's assistant director for records management, Robert P. Finzel, an initial search of records here, conducted several years ago in response to the Chicago lawsuits, turned up signs of only two or three surreptitious entries.

But then, a former FBI agent, M. Wesley Swearingen, who said he worked on the "bag squad" in the Chicago FBI office in the 1950s, charged publicly that the bureau was not being candid, He said he had participated personally in about 300 bag jobs, according to one of the attorneys familiar with his testimony. as a result, Finzel said, a member of the FBI legal counsel's office began poring over a special "sensitive source" card index in the bureau's vast files here, checked the symbols for Chicago, and pinpointed about 50 "sources" that "could likely have been entries."

After further investigation in Chicago, including personal attendance at some depositions in the lawsuits, the agent concluded "that there had obviously been a fairly extensive number" and, Finzel said, recommended that the government agree to the stipulation. But the documentation for 500 separate entires, he said is "certainly not in headquarters files."

According to the government-endorsed stipulation, however, "documentation still exists" for that many black-bag jobs, all aimed at approximately 50 targets "who today would fit the definition of a U.S. person," such as the Chicago Committee to Defend the Bill of Rights and the Midwest Committe for Protection of the Foreign Born, the targets of the Feb. 10, 1962, break-ins.

"There may have been additional black-bag jobs, the documentation of which has been destroyed or cannot be located," the stipulation continues.

The litigation was brought in the mid-1970s by dozens of individuals and organizations led by the Alliance to End Repression, an activist group that had been critical of Chicago police performance, and the American Civil Liberties Union.

Chicago lawyer Douglas W. Cassell Jr., one of the main attorneys in the case, said he had no doubt that FBI files in Washington represent "a bit of a brick wall" as far as black-bag jobs are concerned. He said one "central file which purportedly contained a lot of information about bag jobs" was destroyed in 1977 by an FBI veteran who contended that it was no longer needed.

But the documentation, he said, still exists in the "special safe of the agent in charge" of the Chicago FBI field office, and perhaps other main FBI offices around the country that once had special "bag squads," such as New York and Los Angeles.

Cassell said he had compiled scattered evidence of only about three dozen break-ins in the Chicago case by early 1980, when he decided to ask for everything on the subject in the special safe.

"At first, they [government lawyers] indicated there were a lot, and I said how many is a lot." dickering produced the final admission of "at least 500." In turn, Cassell and his colleagues agreed not to contest, the government's claim of national security privilege for the documentation.

Nationwide, there could have been thousands before Hoover ostensibly called for an end to the practice in 1966, Cassell said. "The Chicago 'bag squad' had about 20 agents" at one point, and the squads in New York and probably Los Angeles were both bigger, he said.

"These were fulltime 'bag-squads,'" Cassell said he learned in the course of the litigation. "That's what they did as their principal responsibility . . . . Each bag job takes eight to 12 agents to pull off. They would have lookouts, people watching out for trouble, all over the place."

By that standard, he estimated, one Chicago-sized squad "is good for maybe about two bag jobs a day or two at the same time."

How many were pulled off? "Swearingen says thousands," Cassell replied. "If they did at least 500 in Chicago. . . . well, you figure it out."