By Dan Collyns
BBC News, Lima
Former PM Jorge del Castillo (L) was mentioned in two of the tapes
Peru's attorney-general has presented charges against eight people accused of illegally recording telephone calls in a scandal that made the cabinet resign.
Most are serving or former naval officers, who are said to have worked part-time for private security firms.
Audio tapes leaked to the media in October implicated members of the governing Apra party in the rigging of multi-million dollar oil contracts.
The corruption allegations, which the cabinet denied, led to public protests.
President Alan Garcia subsequently appointed Yehude Simon, a leftist provincial governor from outside the Apra party, as prime minister.
The investigation into phone-tapping by Attorney-General Gladys Echaiz follows the worst corruption scandal since Mr Garcia took office more than two years ago.
In October, recordings leaked to the press linked members of the Apra party to alleged plans to accept bribes for steering oil contracts to favoured bidders.
An oil company allegedly paid a security firm for the phone-taps
The scandal forced the former Prime Minister, Jorge del Castillo, and his entire cabinet to step down, although several ministers were later reinstated.
Now it has been revealed that serving and former naval officers allegedly moonlighted as wire-tappers at a private security company owned by Rear Admiral Elias Ponce Feijoo, who was demoted by the president last week.
The authorities have seized equipment from Business Track SAC and judges say just a fraction of it has revealed evidence that around 30 high-ranking politicians, lawyers and businessman were phone-tapped as part of a commercial business, for unknown clients.
Among the phone-tapping victims is the president's private secretary, Luis Nava. Local media are speculating that Mr Garcia himself may also have been a victim.
A judge must ratify the charges against the eight men.
Allegations have been made that an oil company paid for phone-tapping so it could get potentially damaging material to blackmail decision-makers or rival firms involved in the competitive auction for oil contracts.
The company has denied any wrongdoing, but it appears there were also many other clients.
Phone-tapping by the intelligence services under President Alberto Fujimori in the 1990s was seen to be common practice.
Now many Peruvians are disillusioned to see it is still prevalent and is being used for corrupt or commercial ends.
This investigation has so far helped the government control the damage to its reputation, but some analysts are saying what has been revealed so far is only the tip of the iceberg.