A judge in Guatemala has ordered the alleged leader of a customs corruption scandal to be held in protective isolation at a maximum security prison amid fears for his life.

Juan Carlos Monzon Rojas appeared in court Tuesday wearing a bullet-proof vest and a military helmet.

Monzon Rojas has said former President Otto Perez Molina and former Vice-President Roxana Baldetti directed the corruption scheme.

Monzon Rojas was Baldetti's former personal secretary, and turned himself in Sunday.

He says he was just following orders in the scheme, in which businesses allegedly paid kickbacks to officials in exchange for lower import duties.

Monzon Rojas faces charges of customs fraud, bribery and criminal organization. He said he feared for his safety and asked the court for security.