Testifying before one Senate committee yesterday, a former high-ranking Central Intelligence Agency official sharply denounced the investigations of the agency in recent years as an "inexcusable exercise in political sensationalism."

Called to another hearing at the same time, the No. 2 man at the FBI acknowledged in laconic tones that the bureau still has no internal rules for its undercover informants, not even in relation to "illegal activities."

The illicit domestic spying and the assassination plots of the CIA, the black-bag jobs and smear campaigns of the FBI, along with a wide variety of other misdeeds, were laid out in painstaking detail during congressional and executive branch inquiries that were in full swing just three years ago. But legislative remedies were held back, for more cautious study.

Now it appears that there will be no charters for the CIA or the FBI coming off Capitol Hill until next year at the earliest. Yesterday's hearings, one conducted by the Senate Intelligence Committee and the other by the Judiciary Committee, illustrated the difficulties. There is as much talk these days of giving the nation's intelligence community a stronger hand as there is of bringing it under control. The abuses of the past are dismissed almost in passing, as though they could never happen again, even without new laws.

The most outspoken witness at yesterday's committee sessions was Thomas H. Karamessines, who served as head of the CIA's directorate of plans, also once known as the Department of Dirty Tricks, before his retirement in 1973.

He protested that the committee's proposed charter for the CIA - already criticized in other quarters as too weak and permissive - wold cripple the agency under a barrage of unnecessary restrictions.

A veteran of 22 years with the CIA, Karamessines conceded briefly that there had been abuses and mistakes in the past, but insisted they were "few indeed," and charged that they 76 Senate inquiry headed by Frank had been brought out during the 1975-Church (D-Idaho) "in an injudicious manner and with an unparalleled display of vehemence."

"The Central Intelligence Agency and our general intelligence capability will be paying, for some years, for this inexcusable exercise in political senationalism," Karamessines said after asserting that the CIA had, afterall, just been following orders. He said he just hoped that "out of this turmoil" would come a recognition of the need for a stronger charter rather than a weaker one.

Complaining of all the certifications and reports required in the Senate bill to insure meaningful oversight, Karamessines said: "If we adhere to this bureaucratic avalanche of paper, we will smother initiative, imagination and energy."

As examples of the changes he has in mind, Karamessines suggested that Congress give the CIA better "cover" or official disguises abroad, that it impose prison penalties for the "unauthorized revelation or compromise" of CIA secrets, and that it even permit the Senate and House intelligence committees to protect CIA employes from other congressional committees.

"I make this recommendation having in mind the wholly senseless miscarriage of justice in the case of Richard Helms," Karamessines said of his former boss's recent misdemeanor conviction for lying to the Senate Foreign Relations Committee in 1973.

MEANWHILE, A BLOCK TO THE EAST IN THE Dirksen Senate Office Building, FBI Associate Director James B. Adams appeared before the acting chairman of the judiciary committee, Sen. Edward M. Kennedy (D-Mass.), who has expressed interest in developing a legislative charter for the FBI's criinal investigations, including domestic security cases.

The Justice Department has ostensibly had a task force at work on the problem for the past two years, but it was not until last week, under prodding from Kennedy, that Attorney General Griffin B. Bell promised to produce some recommendations by a date certain: July 1.

Invited back for further questioning, Adams - who is under internal FBI scrutiny for supplying congressional investigators with an incomplete accounting of the bureau's allegedlly illegal break-ins - made plain that there would be gaps in the July 1 proposals.

The recommendations, for instance, will not include anything governing FBI informants. Asked by Kennedy whether the bureau had any rules for their conduct, "especially with relationto illegal activities," Adams replied it did not.

The Justice Department "has handled these matters on an ad hock basis," Adams reported, adding that FBI and Justice officials contact each other so often about such questions that they've thought of digging a tunnel between the two buildings.

There were, to be sure, witnesses at both hearings in favor of tighter controls. Former CIA director of research Herbert Scoville Jr. told the Intelligence Committee that he felt "a clean break with the past" - by abandoning covert operations - would be best, for the CIA and for the country. Three American Civil Liberties Union witnesses urged the Judiciary Committee to restrict the FBI's use of informers by adopting the use of warrants.

"The FBI record on the use of paid informers in political groups shows a massive violation of First Amendment rights," the ACLU's Jerry Bergman testified.

The memory of past misdeeds, however, is growing dim. The "intelligence community" is, plainly, playing a waiting game. So far, it seems to be winning.