Zimbabwe security forces were on alert for unrest by “malcontents and mischief-makers” following Friday’s verdict in the treason trial of opposition leader Morgan Tsvangirai, the home affairs minister said. Tsvangirai, whose Movement for Democratic Change (MDC) poses the biggest threat to President Robert Mugabe’s 24-year hold on power, faces a possible death sentence on charges of plotting to kill Mugabe and seize power.

Home Affairs Minister Kembo Mohadi said intelligence reports indicated some malcontents and mischief-makers, whatever the decision of the court, are determined to ensure that there is lawlessness within the vicinity of the High Court and in other parts of the country.

“Those with an inclination towards disorder are strongly warned against such behaviour and law abiding citizens are assured of peace and security. We will be on standby countrywide,” Mohadi told a news conference on Thursday. The MDC has dismissed the trial as a charade intended to crush its 5-year-old challenge to Mugabe’s rule. It said in a statement that democracy was on trial in the southern African country. Political analysts say if Tsvangirai is imprisoned or sentenced to death, the MDC would be weakened by a leadership struggle.

“The cohesion that he has managed to maintain around his leadership would be affected, and the MDC would need to find new strength to keep its fight for a democratic system in Zimbabwe,” said Lovemore Madhuku, chairman of political pressure group National Constitutional Assembly. In a statement on the court ruling, the MDC’s national executive council said it would rally behind Tsvangirai, a 52-year-old former trade unionist. “The council reaffirmed the MDC view that it is democracy on trial, not the president as an individual,” it said. “The MDC national council resolved that it will stand in solidarity with the president on judgment day.” Tsvangirai faces separate treason charges linked to anti-Mugabe protests the MDC tried to organise in June 2003.

The state case against Tsvangirai in the main trial rests on a secretly taped video of a Montreal meeting between him and Canada-based political consultant Ari Ben-Menashe, where prosecutors say Mugabe’s “elimination” was discussed. Defence lawyers say Tsvangirai discussed suggestions Mugabe might accept a plan to retire before March 2002 presidential polls. Mugabe won that vote amid charges of rigging from the MDC and some Western nations. Tsvangirai has challenged the result. In a trial that stretched for a year to February this year, chief defence lawyer George Bizos – who defended Nelson Mandela in South Africa’s 1960s treason charges – attacked the credibility of Ben-Menashe, the state’s key witness.

Bizos said the defence showed Ben-Menashe’s evidence was “fatally flawed”, that he had set out to entrap Tsvangirai for financial gain, and that the video had been tampered with. “We have proved that he is a brazen liar. He brazenly lied out of court, and he brazenly lied in court,” Bizos said.

Zimbabwe’s chief prosecutor Bharat Patel argued the state had produced enough evidence to show Tsvangirai held three meetings with Ben-Menashe in pursuit of the assassination plot. “If one makes a request to another person to assassinate a head of state ... that is treason,” Patel said.

High Court Judge President Paddington Garwe heard the case with two civilian assessors. Mugabe, 80, has ruled Zimbabwe since independence from Britain in 1980. The former guerrilla leader says Tsvangirai is a puppet of Western powers seeking to overthrow him for seizing farms from whites for redistribution to landless blacks.