Switzerland's intelligence agency has issued warnings to the United States and Britain of a massive data leak that involved counter-terrorism information. According to reports, the individual responsible for the leak was planning to sell the information to other governments or commercial buyers.

The data leak was reported by the Nachrichtendienst des Bundes, or NDB, Switzerland's intelligence agency, reports Reuters. According to the NDB, a senior IT technician had stolen the counter-terrorism data and was arrested last summer. According to Swiss officials, the technician, whose name has not been released, was reportedly acting suspicious which prompted his arrest. He was later released, and his case is currently being investigated as a criminal matter by the Federal Attorney General.

The technician, who had been working at the NDB for eight years, reportedly became unhappy with officials after he believed they were not listening to his input and advice on data systems operations, notes Reuters. Feeling marginalized, the technician began to download terrabytes of classified counter-terrorism information. The terrabytes of data would add up to millions of pages of classified information that was shared between Switzerland's NDB, United States' Central Intelligence Agency, Britain's Secret Intelligence Service and several other countries' intelligence agencies.

The technician would download the classified counter-terrorism information to portable hard drives and would simply walk out of the building with the data in his backpack. He was able to get the data, because he had administrator privileges, which allowed access to pretty much every NDB network.

When Swiss officials arrested the technician, they also obtained the hard drives that contained the classified information, reports Reuters. The NDB believes that they had arrested the technician before he had a chance to sell the information to interested parties, although they could not be certain and hence the warning to other intelligence agencies.

The NDB was founded in 2010, and this data leak has led to concern about the organization's infrastructure.

According to a source that spoke to Reuters, NDB's organization needs improvement as the technician showed signs prior to being arrested that should have been caught by officials. Among the signs missed by officials, Reuters' source said the technician reportedly would not show up to work after he had become disgruntled.