Belgian authorities said Wednesday they are investigating the origin of espionage software that was left in Prime Minister Elio Di Rupo's office to secretly monitor his activities.
The federal prosecutor's office said it also was looking into a separate, more recent hacking attack, which apparently was aimed at blocking government sites and not linked to spying itself.
Thomas Mels, Di Rupo's spokesman, said that in 2012 officials found the "intrusive software which gathered information and sent it through to a server from whoever put the software there in the first place."
Wenke Roggen of the prosecution's office said the investigation into the origins of the software was still ongoing, and he could not comment further.
Recently, some European countries have complained about secret surveillance of their top officials and citizens in the wake of revelations about a far-reaching spying program by the U.S. National Security Agency.
Belgium has not accused the U.S. of any wrongdoing.
Like other EU leaders, Di Rupo has expressed anger over reports of U.S. electronic espionage overseas and said the Obama administration should agree by year's end to stop alleged American eavesdropping on foreign leaders, businesses and law-abiding citizens.
Last week, Finland, another European Union nation, said its computer networks had been widely hacked but said no highly sensitive information was lost.
Since the discovery in Di Rupo's office, the Belgian government has improved and sped up its cybersecurity strategy, committing 10 million euros ($13.5 million) annually to counter any spying or computer hacking.
Di Rupo also now asks government ministers to leave their mobile phones outside his office during sensitive meetings there.
Explore further: Finland says it was target of "massive" digital spying