Lawyers representing Zimbabwe's opposition leader and two colleagues on trial for treason say some of their confidential papers were taken by a police officer and photocopied.
At the end of a hearing, defense attorney Chris Andersen told the court a six-page statement it was waiting for was intercepted by a policeman, copied, and distributed.
Judge Paddington Garwe said Tuesday's court session will begin with a discussion of the alleged document theft.
Most of the day's session was taken up by the testimony of the head of Zimbabwe's Central Intelligence Organization, Brigadier Happyton Bonyongwe.
He testified that a Canadian consultant who made the videotape at the heart of the state's case switched sides, after being hired by the opposition he began working for the government.
The consultant, Ari Ben Menashe, was the state's first witness when the trial began in February. He was questioned extensively as the court watched the videotape, in which the state claims opposition leader Morgan Tsvangirai plotted to assassinate President Robert Mugabe.
The opposition said last week it had sued Mr. Ben Menashe in Canada to recover money it says it paid him for lobbying work to promote its image in North America.
The treason trial is one of several High Court actions in which the opposition Movement for Democratic Change is a major player.
Last Friday, Mr. Tsvangirai asked a High Court judge to recuse himself from a hearing related to the opposition's challenge of last year's presidential-election results.
The papers say the judge, Ben Hlatwayo, has received a formerly white-owned farm as part of the government's land reform program. The opposition says that calls his impartiality into question
Mr. Tsvangirai's has filed papers to force the High Court to set a trial date, after many delays.
Meanwhile, in the same court building, another trial is reaching a crucial stage. An opposition member of parliament is charged with murdering a ruling Zanu PF party supporter nearly two-years ago. The government has used the killing to justify its claim that the opposition is a terrorist organization.
The only evidence the state has produced so far are statements made by two of the accused who said they were tortured into making confessions.