The High Court judge in Zimbabwean politician Roy Bennett's terrorism trial refused to step aside Monday after the defence said it feared he might be biased against the deputy agriculture minister-designate.

Bennett, 52, is on trial for allegedly plotting to overthrow President Robert Mugabe's government in 2006. His Movement for Democratic Change (MDC) party says the charges are a political ploy to prevent the white farmer from taking up his post in the nine-month-old unity government.

Mugabe's opponents have often been charged with plotting insurgency, but none of the charges ever stuck.

Bennett's lawyers last week asked Judge Chinembiri Bhunu whether he could hand over to another judge saying his handling of a related 2006 trial showed he might be "prejudicial" to Bennett.

But Bhunu refused on Monday, saying the case of Peter Hitschmann and Bennett were separate.

Hitschmann, an arms dealer, was arrested in 2005 and sentenced to 30 months in prison on weapons possession charges. He says that while in detention, he incriminated Bennett in a plot against the government. He has since retracted the confession.

Last week, Bhunu dismissed the defence's concerns over the state's use of Hitschmann's confession in its case against Bennett.

Bennett was finally charged in court Monday with being the financier of a plot with Hitschmann to acquire weapons for purposes of assassinating unnamed persons in the government and overthrow it.

Some of the charges carry the death penalty.

He pleaded not guilty.

The court also began hearing evidence Monday for the first time since it started a week ago. The state called a policeman as a witness.

Meanwhile, about 60 lawyers in their black gowns attended Monday's proceedings in support of Hitschmann's lawyer Mordecai Mahlangu, who was arrested two weeks ago on charges of interfering with the course of justice.

Mahlangu was arrested for writing a letter to attorney general Johannes Tomana, a Mugabe appointee, saying Hitschmann had no evidence to offer in the trial.

He was remanded in custody.

The lawyers planned a solidarity protest march in Harare later in the afternoon.

The Bennett case has deepened tensions in the rocky coalition between Prime Minister Morgan Tsvangirai's MDC and Mugabe's Zanu-PF.

The MDC withdrew from cabinet meetings for three weeks in protest over the case and over Zanu-PF's obstructionist attitude to the implementation of human rights reforms.