Zimbabwe on Wednesday filed treason charges against dozens of political activists accused of plotting anti-government protests similar to those that toppled leaders in Egypt and Tunisia.

Police said they arrested 46 people in Harare on Saturday as they watched videos of protests in the north African countries and discussed possible demonstrations in Zimbabwe where President Robert Mugabe, 87, has held power for 31 years.

They were charged with treason, and we will be coming back to court tomorrow for a bail application, defence lawyer Alec Muchadehama told Reuters.

The charge carries a possible death sentence. Muchadehama said the accused would plead not guilty when the case goes to trial. No date has been fixed yet.

Defence lawyers have said the accused were in an academic debate on African politics when police arrested them.

Those held include trade unionists, student leaders and Munyaradzi Gwisai, who heads a small but radical pressure group, the International Socialist Organisation. They were detained at a meeting called by Gwisai.

Critics say Mugabe has used tough policing and vote-rigging to keep his grip on power despite an economic crisis in the past decade which many blame on his mismanagement.

Mugabe was forced into a power-sharing government with Prime Minister Morgan Tsvangirai's Movement for Democratic Change about two years ago, and is pressing for fresh elections.

Analysts say this would favour Mugabe's ZANU-PF party if no major political reforms are put in place, including a new constitution and improved voter registration.

Tsvangirai said last week his MDC would boycott any general election called before these reforms were enacted.