East Germany announced today that a leading West German counterespionage official had defected to the Communist state, confirming a burgeoning spy scandal that diplomats here said could seriously undermine western intelligence capabilities.

The official East German news agency ADN said Hans Joachim Tiedge, 48, who disappeared last weekend amid mounting evidence of a hemorrhaging spy ring in Bonn, had asked for political asylum and that authorities were considering his request.

The West German government conceded that Tiedge's defection would cause enormous damage to the country's security because it is assumed that he will betray all of what he learned in nearly two decades of counterespionage work.

For the past four years Tiedge was in charge of tracking East German spies. Security officials said he was entrusted as well with the identities of many western agents and their contacts. His detailed knowledge of West German methods in detecting Communist spies would now enable East Germany to alter espionage tactics and to protect any agents deemed at risk, the sources added.

The shocking disappearance of one of West Germany's chief spy trackers provoked harsh criticism of Bonn's intelligence authorities after it became clear that his superiors had been aware of Tiedge's serious drinking and debt problems but had refused to relieve him of his sensitive duties.

Tiedge's neighbors in Cologne said today that they had complained to his office about his increasingly drunken and disorderly behavior, which worsened after the death of his wife three years ago.

Security experts said the government must now seek to determine whether Tiedge had served as an East German "mole" throughout his career or had changed allegiances after becoming depressed over his wife's death.

In Washington, State Department sources said that reports from the U.S. Embassy in Bonn and the U.S. mission in West Berlin have given no indication that Tiedge's defection poses any significant threat to U.S. intelligence interests. The sources cautioned, though, that State does not always know the full extent of CIA activities in Central and Eastern Europe.

These sources also noted that it has been evident since the 1960s that East Germany has been able to infiltrate the West German government and its security services with relative ease. As a result, the sources added, while the United States maintains intelligence cooperation with Bonn directly and through organizations like NATO, special efforts are made to limit the degree of cooperative efforts and to keep important U.S. intelligence shared with the West Germans restricted to a relatively small circle of senior officials.

In Brussels, however, a NATO intelligence source told Reuter, "On a scale of seriousness from 1 to 10, this (defection) rates 9 1/2."

Hans Neusel, a state secretary in the Interior Ministry, said there were strong indications that Tiedge defected in a moment of panic after cracking under the psychological strain of his problems. But the official did not minimize the importance of the information that could be betrayed by Tiedge, who ranked third in command at the counterintelligence service known as the Office for Protection of the Constitution.

"This case will have serious results for West Germany's security," Neusel told a news conference. "If Tiedge passes on all his knowledge to the opponent secret services this will mean massive damage for West Germany's intelligence work."

Neusel said that the government had undertaken emergency measures to protect people whose work and lives could be jeopardized by Tiedge's defection. He said the Bonn government also would carry out an urgent rehabilitation of its counterintelligence operations against East Germany.

Tiedge's treachery swelled speculation that he might have tipped off three other spy suspects, including the personal secretary of Economics Minister Martin Bangemann, who have disappeared this month. All three are believed to have sought sanctuary in East Germany, but the Communist authorities have not mentioned their whereabouts.

Tiedge was ostensibly in charge of the hunt for Ursula Richter, an accounts secretary for an East European exile organization in Bonn who was suspected by security forces of acting as a control agent for several East German spies. She vanished last weekend along with her friend Lorenz Betzing, an Army messenger who had once worked inside a top-secret government bunker 20 miles from Bonn that is intended to serve as an underground command post in time of nuclear war.

The third alleged spy, Sonja Lueneburg, a confidant of Economics Minister Bangemann for 12 years, disappeared three weeks ago after telling her office that she was going to Brussels for the weekend with friends. When her story proved false, police searched her apartment and found signs of a hasty departure and espionage devices.

Lueneburg received a promotion last month that required further security checks, and security officials theorized that she feared the false identity she had used to infiltrate into West Germany 20 years ago might have been discovered.

Neusel said that he anticipated a continuing exodus of Communist spies in the coming weeks once Tiedge informs East German authorities about agents who could be close to exposure in West Germany.

The East German news agency declared that Tiedge's defection showed East Germany was "constantly in the picture" regarding West German intelligence work. East Berlin newspapers reported today that 168 West German agents had been captured in the past 18 months.

Neusel confirmed the reports about Tiedge's personal problems but said that the troubled spy hunter would have presented a more severe security risk if removed suddenly from his post.

"If he is sacked you can't imprison him or isolate him because what happens is that you put him in a psychological position where he becomes a real security threat. It's better to look after a man like that than to put him on the street," Neusel said.

Tiedge called in sick on Monday and was later reportedly seen visiting his wife's grave. A nationwide search began on Wednesday when his three daughters filed a "missing person" report. Police were alerted at all border crossings to East Germany, but Neusel said that as an intelligence specialist, Tiedge knew several hidden routes to the East.

Diplomats said that Tiedge's high rank and broad access to sensitive information could compromise the work of the intelligence services of Bonn's western allies, including the United States. They said the allies' network of intelligence data, particularly concerning East Germany, where the West Germans share a common language and culture, was sufficiently broad that Tiedge could impair certain allied functions.

Security experts say the current scandal is the worst espionage blow to West Germany since 1961, when Heinz Felfe, a senior officer in the foreign secret service, was arrested as an agent of the Soviet security service KGB.

The Tiedge affair also is being likened in terms of political volatility to the case of Guenter Guillaume, a close aide to former chancellor Willy Brandt. Brandt was forced to resign from office after Guillaume was unmasked as an East German spy in 1974.

Earlier this week, Chancellor Helmut Kohl tried to deflect the scandal's political consequences in a television interview by suggesting that its roots trace back to previous governments. "If someone plans 30 years ahead, provides agents with a completely new identity, infiltrates them into West Germany through foreign countries and builds up his network, he has naturally got good chances of putting his people into place," Kohl said.

Diplomats said that while Kohl may not be personally implicated in the scandal, Bangemann's connection to Lueneburg could become a serious political liability for himself as well as for the Free Democratic Party he now heads.