Italian police on Tuesday announced the arrest of a London-resident nuclear engineer and his sister on suspicion of running a cyber snooping operation targeting politicians, public bodies and companies.

Police did not name the two suspects but Italian media cited charge sheets which identified them as Giulio Occhionero, 45, and his sister Francesca Maria Occhionero.

Reports described the pair as well known figures in Roman finance circles who lived in the Italian capital but were officially resident in London.

Media reports said politicians targeted by the pair included former premiers Matteo Renzi and Mario Monti and the current head of the European Central Bank (ECB) Mario Draghi.

The brother and sister were placed under investigation last year after a senior government official reported having been sent an email contained spy malware known as EyePyramid.

Prosecutors want them charged with illegally obtaining information related to state security, illegally accessing computer systems and illegal interception of online messages.

Data they collected was allegedly catalogued under two broad categories: BROS for snippets concerning individuals who were members of masonic orders, and POBU for politicians and business figures.

Police said the information trawling was carried out via a complex network of overseas-based companies but did not offer any theory of what the duo's objective might have been.