Three former ministers serving under the previous socialist government, four OTE telecom board members and officials from the ruling New Democracy party are among those allegedly involved in the Siemens bribery scandal, according to sources.

Siemens is believed to have spent more than -100 million over a 17-year period in Greece to bribe local officials in order to secure state contracts through its Greek unit, Siemens Hellas.

According to sources close to the investigation, authorities in Munich, Germany, have collected enough evidence to prosecute some of those allegedly on the receiving end of bribes.

Handwritten notes from Siemens staff members, naming alleged recipients, and testimony from company officials on how bribes were paid are included in the evidence gathered so far, sources added.

Once the testimony of all involved is concluded, prosecutors are likely to charge suspects with bribery, forming a criminal gang, committing fraud against the Greek state and money laundering.

Siemens, one of the world's largest electrical and industrial engineering companies, has allegedly paid hundreds of millions of euros in bribes across the world. Siemens was involved in the C4I surveillance system bought by Greece for more than -250 million ahead of the Athens 2004 Olympics. It has been suggested that this is one of the deals that prosecutors will be probing in connection to the graft claims.