The men say they are merely mine security guards

The men were charged with conspiring against the government of Equatorial Guinea and other offences including violation of immigration laws.

The defendants, mainly from South Africa, are being held at Chikurubi jail just outside the capital, Harare.

Their plane landed at Harare international airport two weeks ago.

Appearance

The men, many of them former members of South Africa's apartheid-era military forces, were herded into the makeshift courtroom in handcuffs and were dressed in khaki jail uniforms.

Making their first court appeance since their arrest, they said nothing. Many were barefoot.

Chief prosecutor Mary Zimba-Dube said they faced life imprisonment if found guilty, but defence lawyer Jonathan Samkange told reporters his clients faced maximum fines of $200,000 each.

The suspects were not asked to make a plea and have now been remanded until mid-April.

The prosecutor accused Simon Mann from Britain of being the ringleader of the group and said he acted on instructions from exiled Equatorial Guinea opposition leader Severo Moto.

The men's lawyers had appealed for trial in an open court, but the judge ruled that prison was the only suitable place for a trial, because of "serious security concerns".

State prosecutors had warned the court that external groups had the capability of launching an airborne rescue mission.

The men say they are merely mine security guards.

Another 15 men are being held in Equatorial Guinea, linked to the same alleged plot.