Britain's biggest arms manufacturer BAE secretly sold mass surveillance technology to six Middle Eastern governments repeatedly condemned for repressing their citizens, according to documents seen by the BBC BAE bought the surveillance system 'Evident' from a small Danish company called ETI in 2011 after it was used to crackdown on opponents of Tunisian President Zine al-Abidine Ben Ali, who was ousted by the first uprising of the Arab Spring that same year. The arms company, now known as BAE Systems Applied Intelligence, then sold the technology to the governments of Saudi Arabia, UAE, Oman, Qatar, Algeria and Morocco. A former Tunisian intelligence official told the BBC how he used the system to track opponents of the then President Ben Ali. "ETI installed it and engineers came for training sessions," he said. "[It] works with keywords. You put in an opponent's name and you will see all the sites, blogs, social networks related to that user." A second employee who worked closely with Ben Ali said: "Sometimes they would ask me to get information about specific people...some information used to go directly to the president. Most of this was about his opponents." The system can collate and analyse millions of people's electronic communications. Human rights campaigners have warned for years that the technology is being used to track down and imprison dissenting citizens of authoritarian regimes. A former ETI employee who developed Evident described its vast surveillance capabilities: "You'd be able to intercept any internet traffic," he said. "If you wanted to do a whole country, you could. You could pinpoint people's location based on cellular data. You could follow people around. They were quite far ahead with voice recognition. They were capable of decrypting stuff as well." Activists in Saudi Arabia told the BBC of the intense repression made possible by such advanced spying technology. "I wouldn't be exaggerating if I said more than 90% of the most active campaigners in 2011 have now vanished," said Saudi former air force officer Yahya Assiri, who was forced to flee the country after airing pro-democracy views online. "It used to be that 'the walls have ears', but now it's 'smartphones have ears,'" said Manal al-Sharif, a Saudi women's rights activist who now also lives abroad. "No country monitors its own people the way they do in the Gulf countries," she said. "They have the money, so they can buy advanced surveillance software." The sales were legal but made despite the British government's long time acknowledgement of the deadly repression meted out by the Middle Eastern governments, and its pledge of support for the Arab Spring. In 2011, the year BAE purchased the spying system, then Prime Minister David Cameron declared the government had made the wrong choice in 'backing authoritarian regimes in the Gulf states', and said British interests instead "lie in upholding our values – in insisting on the right to peaceful protest, in freedom of speech and the internet, in freedom of assembly and the rule of law." BAE defended its sales of mass surveillance technology, stating: "We have robust policies and procedures in place to ensure our international exports to overseas governments are all fully compliant with international export regulations as well as our own strict criteria to evaluate every potential contract." The BBC said it had asked the Middle Eastern states to comment but received no response.