West German Chancellor Helmut Kohl said today it was "utterly incomprehensible" that Hans Joachim Tiedge, who was in charge of tracking East German spies until his defection last week, was retained in his sensitive post despite serious drinking and debt problems known to his superiors.

Friedhelm Ost, the government spokesman, told reporters of Kohl's comments, made at a Cabinet meeting, and said the chancellor was determined to draw the necessary consequences this week from the spy scandal.

Government officials said it appeared almost inevitable that Heribert Hellenbroich, the newly appointed head of foreign intelligence, would have to resign. He served as chief of counterespionage until Aug. 1. While aware of Tiedge's personal difficulties, Hellenbroich said he did not fire or transfer his friend because he feared Tiedge's resulting dismay might have made him a security risk.

The opposition Social Democrats insist that Interior Minister Friedrich Zimmermann should step down out of a sense of political responsibility for what they call the country's gravest security disaster. Hans-Jochen Vogel, the party's parliamentary leader, has vowed to call an emergency session of the Bundestag, or parliament, if the minister remains in office.

Zimmermann, whose right-wing views are anathema to many Social Democrats, has said he was not told of Tiedge's troubles until two days after the defector disappeared. Government officials predicted that Kohl would not dismiss Zimmermann, if only to avoid another row within the fractious center-right ruling coalition.

The chancellor's decision to retain Zimmermann is likely to soothe the minister's Christian Social Union, the Bavarian sister party of Kohl's Christian Democrats. The Christian Social Union, headed by Kohl's rival Franz Josef Strauss, repeatedly has quarreled with the junior coalition partner, the Free Democratic Party, and called into question Kohl's leadership capabilities.

By refusing to succumb to the opposition's demands to fire Zimmermann, Kohl not only would shore up his right political flank but also draw a clear distinction between the present furor and espionage scandals that plagued the Social Democrats when they held power in the 1970s.

In 1974, the exposure of Guenter Guillaume, a trusted aide of then-chancellor Willy Brandt, as an East German spy was a major factor in Brandt's resignation. The Social Democrats have sought to imply that the Tiedge affair has inflicted much greater damage on western security interests than the Guillaume case, but Kohl has been able to reject direct political responsibility because none of his advisers appears to be implicated in the latest scandal.

Despite the political sniping, leading figures in all West German parties have sought to insulate diplomatic and economic ties between the two German states from the shock of the spy scandal.

Apart from Tiedge's betrayal, the espionage crisis has involved the exposure of four other East German agents in Bonn, including two secretaries with access for many years to highly classified information.

Kohl has muted his early criticism of East Germany's massive spy infiltration network, and the Bonn government has tried to present a "business-as-usual" attitude toward relations with the communist authorities.

Ost announced today that Dieter von Wuerzen, a state secretary in the Economics Ministry, would attend the Leipzig trade fair next week. The forum has become an important showcase attracting entrepreneurs seeking trade deals and politicians exploring prospects for further rapprochement between the two German states.

Usually, Bonn's government is represented at the fair by its economics minister, now Martin Bangemann. He was forced to decline this year's invitation when his private secretary for the past 12 years vanished earlier this month amid suspicions that she had worked as an East German spy.

The Social Democrats have said that Brandt, now party chairman, still intends to visit East Berlin in September and plans to meet East German leader Erich Honecker. It will be Brandt's first trip to East Germany since he resigned as chancellor.

Even Strauss, the conservative Bavarian premier once known as a cold warrior, has contended that relations with East Germany should not suffer because of the gaffes committed during the current scandal by the West German counterespionage service.

East Germany also has indicated that it would prefer to defuse any political tensions caused by the spy controversy. Specialists on Soviet Bloc affairs say it was interesting that unlike previous cases when agents fled to the East, none of the four suspected spies who have fled, including Tiedge, has appeared on East German television yet to denounce the evils of living in the West. One suspect is in custody here.

Last Thursday, a day before East Germany announced that Tiedge had defected, the official Communist Party newspaper Neues Deutschland published a report noting that 168 West German agents had been captured in East Germany since the beginning of 1984.

The report went on to contend that "only the sober-minded policies of the German Democratic Republic did not allow these arrests to hurt relations." Unlike previous espionage coups, the newspaper has not trumpeted Tiedge's defection as a major vindication of the Communist system.

Soviet Bloc specialists said the low profile adopted by the East German state-controlled media provides clear evidence that the authorities want to soften the impact of the spy hunter's defection.

Ost also said today that the West German government still was attempting to arrange an audience with Tiedge, reportedly through East German lawyer Wolfgang Vogel, who arranges releases of refugees and spies. But Bonn officials said a message, purportedly from Tiedge, was sent back spurning the idea.