The NSA has announced its brainwave to end further leaks about its secret operations by disaffected employees: it will simply sack 90 per cent of all its sysadmins.

The US surveillance agency's spyboss General Keith Alexander told a computer security conference in New York that automating much of his organisation's work - such as snooping on anyone with an internet connection - will make it more secure.

The inner workings of the NSA's massive PRISM and XKEYSCORE programmes were exposed to the world by Edward Snowden, an ex-CIA techie and NSA contractor who had access to highly classified material, along with about 1,000 other sysadmins.

Gen Alexander said: "What we're in the process of doing - not fast enough - is reducing our system administrators by about 90 percent."

Until now, the chief spook continued, the NSA has "put people in the loop of transferring data, securing networks and doing things that machines are probably better at doing".

Replacing these leaky humans with computers would make the spooks' work "more defensible and more secure". However, the general said his agency had been planning these changes for some time. He did not refer to Snowden by name while announcing his layoffs.

The head spook has previously discussed security measures employed by the agency, such as the requiring the presence of two people before certain sensitive data can be accessed.

"At the end of the day it's about people and trust," Gen Alexander added. "No one [at the NSA] has wilfully or knowingly disobeyed the law or tried to invade your civil liberties or privacies. There were no mistakes like that at all." ®