The men have been held since March

Former British SAS captain Simon Mann admitted trying to procure dangerous weapons - a charge which carries a possible 10-year jail sentence.

The men's plane was impounded in March, when they picked up weapons bought from the Zimbabwe state arms supplier.

All but three pleaded guilty to lesser charges on Tuesday.

Death penalty

Simon Mann also entered a limited guilty plea to a second charge of purchasing weapons, but insisted that the deal never went through, Reuters news agency reported.

Prosecutors called the marketing manager at Zimbabwe's state arms manufacturer to testify on Wednesday.

Hope Mutize told the court that Mr Mann had said he wanted to buy some weapons - and had put a deposit down.

"According to him, he wanted to use the weapons to guard mines in the DR Congo," Mr Mutize said, according to AFP news agency.

E Guinea: Ripe for coup Who are the detained men?

The group have maintained all along they were going to the Democratic Republic of Congo to provide security for mining operations.

On Tuesday, three men including Mr Mann did not face the aviation and immigration charges because they were already in Zimbabwe when the plane landed.

These lesser charges carry small fines or short prison terms, the AFP news agency reports.

But correspondents say the real question is whether they will be extradited to Equatorial Guinea, where they could face the death penalty.

The governments of South Africa, Zimbabwe and Equatorial Guinea believe they were heading to the small, oil-rich country to overthrow the government.

Razor wire

The BBC's Alastair Leithead in Johannesburg says there is much confusion surrounding the alleged coup plot and how the men came to be arrested.

The trial is being held in a building inside a high-security prison surrounded by high concrete walls and razor wire.

The men, who have been held for four-and-a-half months with restricted access to lawyers and relatives, have complained about prison conditions.

Following their arrest in March, they had claimed they were tortured by Zimbabwean security agents.

The Zimbabwean government recently signed an extradition deal with Equatorial Guinea, where other South Africans are being held on suspicion of being the advanced party in the alleged plot.

The group's lawyers have appealed to the South African government to extradite them there instead, so they would not face a possible death penalty.

But South African state lawyers have opposed this legal request and the constitutional court is to deliver its decision.