Harare - Dozens of foreigners held in Zimbabwe on suspicion of being mercenaries could face the death penalty, Foreign Minister Stan Mudenge said on Wednesday.

"They are going to face the severest punishment available in our statutes, including capital punishment," Mudenge told a news briefing. "We will give them all the rights they are entitled to."

Zimbabwe detained 64 men on Sunday after the seizure of a US-registered cargo plane which officials said was carrying "military material". Officials on Tuesday said the suspects were mainly Angolans, South Africans and Namibians.

They said they had also arrested a man identified as Simon Mann, a former member of the Britain's Special Air Service elite forces, and two other men who were at the airport to meet the plane when it landed in Harare on Sunday.

Mudenge said Zimbabwe was in contact with the government of Equatorial Guinea, where officials on Tuesday announced the arrest of 15 suspected foreign mercenaries they described as an advance party connected to the group detained in Harare.

"We are going about it deliberately and we are going to liase with our friends in Equatorial Guinea... with our friends in South Africa," Mudenge said.

"Apparently this was not one mission... after the diversion in Equatorial Guinea they were going to the DRC (Democratic Republic of Congo)," he said.

South African Foreign Ministry officials have said any South Africans involved in mercenary activities were breaking the country's laws.