The supreme court in Zimbabwe Tuesday rejected charges of treason against opposition leader Morgan Tsvangirai, declaring them unconstitutional. The case was initiated by the government of President Robert Mugabe.

In a brief hearing of less than 30 minutes, all five judges of the supreme court, the most senior court in Zimbabwe, agreed that two treason charges against Mr. Tsvangirai infringe his constitutional rights.

The charges against the president of Zimbabwe's main opposition party, the Movement for Democratic Change, date back to a speech he gave last year in which he said President Robert Mugabe would be removed by force if he did not resign voluntarily.

The Mugabe government said the remarks violated the country's Law and Order Maintenance Act, making him guilty of treason.

The supreme court, in a ruling that was in broad agreement with the arguments made by lawyers defending Mr. Tsvangirai, said that people accused under the Law and Order Act are automatically treated as guilty. The judges said this assumption contradicts a basic right of Zimbabwe law that everyone is presumed innocent before being tried.

Mr. Tsvangirai was not in court during the hearing.

The MDC said that although the Supreme Court judgement is a setback for the government, it does not expect any let-up in intimidation or harassment by the authorities.

There have been more than 10 raids by police on MDC offices this year. At least 50 officials, including two members of parliament, have been arrested or detained following the recent death of Cain Nkala, a leader of former guerilla war veterans in the western city of Bulawayo.

Mr. Mugabe has called the MDC a "terrorist organization." At the funeral of Mr. Nkala, he vowed to crush the party completely.

In Harare on Tuesday, a group of pro government militants tried to block MDC members of parliament from entering the parliament building. After a brief demonstration the crowd of about 100 was dispersed by police wearing body armor and the opposition parliamentarians were allowed in.

Meanwhile, the Zimbabwe government has approved a regulation that limits the maximum size of commercial farms to 2,000 hectares.

Agriculture minister Joseph Made said that any extra land must be handed to the government, and that the measure applies to land that is not listed for seizure.

The Commercial Farmers Union said that about 90 percent of the country's 5,000 commercial farms were already targeted for seizure before the new regulation was introduced. Union officials said the latest ruling means that almost all privately owned farm land in Zimbabwe will be nationalized.