In a rare deatailed public statement in the House of Commons about British intelligence, Prime Minister Margaret Thatcher today confirmed recent newspaper charges that the former chief of Britian's M15 counterintelligence service had been investigated as a possible Soviet spy but added that no evidence had been found to incriminate him.

Following a week of sensational allegations about Soviet spies being employed in important positions in the past, Thatcher emphasized her belief that Britainhs twin domestic counter espionage and foreing intelligence services, M15 and M16, are free of the high-level penetrations by Soviet agents discovered and rooted out during the 1950s and 1960s.

But the prime minister also revealed that she has ordered an elite independent commission to review security procedures in Britainhs secret intelligence services and the rest of the government.

Thatcher, in a statement to the hushed, crowded House of Commons, said the late Sir Roger Hollis, who served as the head of M15 from 1956 until his retirement in 1965, had been investigated in the early 1970s. She said the probe "was based on certain leads which suggested, but did not prove that there had been a Russian intelligence service agent at a relatively senior level in British counterintelligence in the last years of the war."

The prime minister said "none of these leads identified Sir Roger Hollis or pointed specifically or solely in his direction. Each of them could also be taken as pointing to "[Kim] Philby or [Anthony] Blunt" -- who had already been discovered to be Soviet moles.'

The investigation of Hollis "did not conclusively prove his innocence; indeed it is very often impossible to prove innocence," Thatcher said. "But no evidence was found that incriminated him, and the conclusion reached at the end of the investigation was that he had not been an agent of the Soviet intelligence service."

This most recent British spy scandal has been making headlines here all week, as the Daily Mail has been serializing a book by its defence specialist, Chapman Pincher, about past infiltration of the British government and intelligence service by the Soviets. Monday's installment detailed the charges against Hollis, even though Pincher conceded that the charges could not be proved.

Thatcher said that the allegations in ypincher's book were "inaccurate or distorted" in part and contained "no information of security significance which is new to security authorities."

Pincher had written that during two separate interrogations, one lasting 48 hours, "Sir Roger never broke," but "his frustrated interrogators believed that they had before them the most successful spy in history -- a KGB agent so successful that he made the notorious spies of the past like [Guy] Burgess and [Donald] Maclean, Philby and Blunt look very much in the second league."

Thatcher acknowledged that the "view" that Hollis was not a Soviet agent was challenged "by a very few of those concerned" and that former Cabinet secretary Lord Trend was asked by then-prime minister Harold Wilson in 1974, a year after Hollis died of a heart attack, "to review in detail the investigations" against Hollis.

After a year's study and interviews cwith many of those concerned, including two people who considered that the investigation should be reopened," she said, Lord Trend "was satisfied that nothing had been covered up. He agreed that none of the relevant leads identified Sir Roger Hollis as an agent of the Russian intelligence service, and that each of them could be explained by reference to Philby or Blunt."

Thatcher emphasized that Pincher "is wrong" in writing that Lord Trend "concluded that there was a strong prima facie case that M15 had been deeply penetrated over many years by someone who was not Blunt" and that Lord Trend "named Hollis as the likeliest suspect."

"Lord Trend said nethier of those thingts and nothing resembling them," Thatcher told Parliament. "Lord Trend, with whom I had discussed the matter, agreed with those who, although it was impossible to prove the negative, concluded that Sir Roger Hollis had not been an agent of the Russian intelligence service."

Trend said tonight, "You may take it that I concur entirely with Mrs. Thatcher's statement. Apart from that, I have no comment."

Former prime minister Wilson, making a rare appearance in Parliament, also said today that nothing in Lord Trend's report would "substantiate any allegations of a coverup."

Thatcher said changes in recruiting procedures and repeated tightening of security precaustions "have over the years substantially reduced the vulnerability of the public service to the threat of penetration." These arrangements should be scrutinized again, she said when announcing her decision to appoint the high-level review commission, because the "techniques of penetration and the nature of the risks may have changed" in the 20 years "since they were last subject to independent review."

The commission will be made up of high court judges and retired government officials and military commanders. It will report back to Tatcher, who said she would make an unprecedented statement on its findings and recommendations to the Parliament.

This action and Thatcherhs statements today were not satisfactory, however, for a minority of parliamentary members from both major parties who wanted her to answer Pincher's charges in more detail and make the intelligence service generally less secretive and more accountable to Parliament. They now answer only in secret to the prime minister, foreign secretary and home secretary. Even the names of the directors of M15, which is responsible for countering espionage, sabotage and subversion in Britain, and M16, which conducts foreign intelligence operations, and the locations of their offices are supposed to be secret.

Thatcher said she did not believe any further changes should be made before the security commission reports back to her. No time limit has been set for its study.

Except for saying that "some of the material [reported by Pincher] is inaccurate or distorted," Thatcher refused to discuss Pincher's other allegations.

They include a charge that journalist and former Labor Party chairman and member of Parliament, Tom Driberg, later known as Lord Bradwell and also now dead, spied simultaneously for Britain, the Soviet Union and Czechoslovakia. Pincher wrote that Driberg, a well-known homosexual, had passed information to the Soviets about the sex lives of British officials and had reported back to British intelligence on meeting in Moscow with his friend Burgess, who had defected from Britain with Maclean in 1951.

Their defection, Thatcher told Parliament today, touched off years of investigations "into the penetration of the secret services and other parts of the public service." It was discovered, she said, that in addition to Philby and Blunt, whose treason has since become known, "there was good reason for suspecting a few others."

"But as it was not possible to secure evidence on which charges could be founded," she added. "They were required to resign or were moved to work where they had no access to classified information. Many others were eliminated for suspicion."

Many of those "named or implicated" in Pincher's book "as having been the subject of investigation have died," Thatcher said."Others have long since retired. None of them are still in the public service."

Thatcher said she would not comment on these "other allegations and insinuations in this book. Nor can I say which allegations are unsubstantiated or true -- as some certainly are -- since by doing so I should implicitly be indicating those which were suspected of having a degree of substance."

Opposition Labor leader Michael Foot, with whom Thatcher consulted before ordering the new review of security procedures, said he supported her statement and noted her characterizations of parts of Pincher's book as "unsubstantiated," "untrue," "inaccurate" and "distorted." He complained that this could cause "individual people to be misjudged and defamed, and people should take this into consideration when writing about the dead as well as the living."

"Pincher defended himself at a press conference arranged by his publisher following today's discussion in Parliament. He said the new inquiry into security procedures "would not have occurred but for the revelations in my book, of which I do not retract a word."

He said the only fact in his book contradicted by Thatcher was his report of Lord Trend's conclusions, which he said came from Lord Trend's own "prime sources." Thatcher's account, he added, had proved only that the investigations of Hollis were "inconclusive," not that he had been completely cleared of suspicion.

He also denied an allegation, in today's edition of the weekly New Statesman magazine, by two other members of Britian's large coterie of journalistic spy hunters that "a substantial amount" of his material came from former CIA official James J. Angleton. New Statesman writers Duncan Campbell and Walter Barre said they had received similar information about the Hollis case "indirectly" but decided against publication because it was inconclusive.

They said, "Pincher's allegations have brought out into the open the enormous split within both the British and U.S. intelligence agencies over the persistent suspicions of KGB moles."

Pincher said today he had received some information for his book from CIA sources but none from Angleton. He would not name his British intelligence sources.

But in his book, Pincher indicated that they believed that the extent of past Soviet infiltration of the British government, including the intelligence services and Parliament, has been covered up.

In Washington, Angleton denied that he had been a source for Pincher. He denounced the reports as an obvious effort ot divert public attention in Britian from the real sources of the information.

"The facts of life are very simple," Angleton said in a telephone interview. "I have never met Pincher nor have I ever discussed with him matters relating to intelligence. He's requested to see me in the past, but I have never met with him. And I have never discussed with him, directly or indirectly, questions relating to my occupation."