BONN, Germany (AP) _ Willy Brandt's widow published part of her husband's political diary Wednesday to back her claim that a colleague betrayed the widely admired West German chancellor to east Germany.

But historians say there's nothing new in the 20-year-old document and that it does not support Brigitte Seebacher-Brandt's claims against parliamentary leader Herbert Wehner.

The back-and-forth is the most serious instance of Germany's divided and painful past being dug up as ammunition for this year's state and national elections.

The diary shows that Brandt didn't trust Wehner, the leader in Parliament of Brandt's Social Democrats. But he never accuses Wehner of being a spy.

Mainly, the entries reveal Brandt's bitterness in the weeks before he stepped down as chancellor in 1974, after an aide - Guenter Guillaume - was revealed to be a member of East Germany's Stasi secret police.

In the entries, Brandt criticizes colleagues and himself for security lapses, and assesses the work of intelligence officials, aides and colleagues such as Wehner.

He writes that he suspects that Guillaume has provided East German President Erich Honecker with evidence of Brandt's marital infidelities and that Honecker in turn leaked this information to Wehner and perhaps indirectly to Guenther Nollau, of west German counterintelligence.

Brandt's widow says Wehner's meetings with Honecker are part of his activities as a spy. Brandt in the diary never makes that claim, although he seems to suspect Wehner used information received from the east against him.

Brandt, who was awarded the Nobel Peace Prize for establishing detente with East Germany, died in 1992. Wehner died in 1990.

Rather than a historical reckoning, the diary publication was seen as a political move by Seebacher-Brandt, a historian and journalist who has been battling her late husband's successors for control of his papers and political legacy.

The Social Democrats say Seebacher-Brandt, 47, is waging a campaign on behalf of Chancellor Helmut Kohl. On Wednesday, they urged her to leave the party and join Kohl's Christian Democrats.

The Christian Democrats say they would welcome Seebacher-Brandt as a member and want a parliamentary commission to investigate her claims.

East Germany had some 500 agents in West Germany, and federal prosecutors have arrested several prominent journalists and politicians in the past few months as spies for the Stasi, or secret police.

Members of Kohl's party say the Social Democrats must answer for the disproportionate number of spies in their ranks and for cosying up to East German officials in the 1970s under Brandt's detente policy.

The diary entries published in the Frankfurter Allgemeine Zeitung on Wednesday begin April 24, 1974, the day that West German agents arrested Guillaume, a Stasi agent in Brandt's office, and end May 6, the day before Brandt resigned.

He and Seebacher-Brandt, his third wife, were married in 1983, nine years after the period covered in the excerpts.

Observers have suggested several theories about why Seebacher-Brandt is releasing the diary excerpts and making apparently inflated claims about their content.

They suggest variously that she is upset that Social Democratic leaders have refused to set up a foundation to house Brandt's papers; that she wants to discredit the Social Democrats in the elections because she believes they are too far to the left; that she wants to buttress Brandt's reputation as a betrayed champion of German unity.