A perjury investigation involving Chancellor Helmut Kohl has been dropped by a state prosecutor in the Rhineland city of Koblenz because of insufficient evidence, a West German government spokesman said today.

Spokesman Friedhelm Ost said Koblenz Chief Prosecutor Hans Seeliger ruled that evidence accumulated during a three-month investigation of alleged irregularities in campaign contributions did not warrant official charges being filed.

Kohl's exoneration comes at a politically opportune time because his Christian Democratic Party is desperately trying to hang on to its majority in a state election in Lower Saxony, to be held June 15.

The announcement also improves Kohl's chances of reelection in national balloting next January, political observers said.

Ost said the conservative chancellor "has taken note of the [Koblenz] decision, which he had expected all along."

Kohl still faces a similar proceeding in Bonn, but legal specialists said that the evidence was much weaker in the Bonn case, and that those charges, too, were likely to be dropped.

[The Bonn prosecutor said today that his office is continuing to pursue the complaint, The Associated Press reported. It added that West German television and a national daily newspaper, Die Welt, reported in recent days that both inquiries would be dropped.]

Both investigations involve allegations that the West German leader lied in testimony given to two separate inquiries, one in the state of Rhineland-Palatinate and the other in the federal Parliament, into whether he accepted illegal political campaign contributions. The Koblenz investigation focused on political contributions made while Kohl was governor of Rhineland-Palatinate state from 1969 to 1976.

Kohl denied any illegalities, but Otto Schily, a Berlin lawyer and leader of the radical Greens party, insisted that he had evidence that perjury had been committed and pressed for the investigations.

[Schily said Wednesday that the Koblenz prosecutor's decision "sanctions the incredible evasive claims" of the chancellor, and that he would appeal it, AP reported.]

Kohl has maintained that the allegations were politically inspired, and he also has predicted that the accusations in Bonn would be dropped for lack of evidence.

Political commentators here had speculated that if Kohl were formally charged in either investigation, he would probably have to step down from the chancellorship until the trials were resolved. Further, it was said, he might have to be replaced as party leader and national candidate by another Christian Democrat if the trials lasted through the election period.

Now, barring a different decision by the Bonn prosecutor, Kohl's standing as party and national leader has been reestablished, according to political observers.