The US National Security Agency failed to install the most up-to-date anti-leak software at a site in Hawaii before contractor Edward Snowden went to work there and downloaded tens of thousands of highly-classified documents. 

Other US government facilities had begun to install software designed to spot attempts by unauthorised people to access or download data.

The purpose of the software made by a division of Raytheon is to block so-called 'insider threats'.

The installation order from President Obama was to tighten up controls after Wilkileaks published huge tranches of confidential US files onllne from leaks by jailed private Bradley Manning in 2010.  

US officials told Reuters the software was not set up at the NSA in Hawaii because there was insufficient bandwidth to comfortably install it and ensure its effective operation. 

Due to the bandwidth issue, intelligence agencies in general moved more slowly than non-spy government units to install anti-leak software, officials said.

Previous reports have suggested that Mr Snowden benefited from antiquated security systems to rummage through NSA systems.

A spokeswoman for the NSA declined to discuss details of the agency's schedule for installing anti-leak software in Hawaii.

She said the agency has had to speed up its efforts to tighten security in the wake of Mr Snowden's disclosures.

"We open our facilities only after we have met all of the necessary regulatory, statutory, and infrastructure requirements," the spokeswoman said.

"NSA has a very large, diverse and complex IT infrastructure across our global enterprise, and many features of that infrastructure evolve overtime as new capabilities are developed, refined, and deployed."

She added: "NSA and the Intelligence Community (IC) at large have been moving forward with IT efficiency initiatives for several years. The unauthorised disclosures have naturally compelled the NSA and the rest of the IC to accelerate the timeline."

The NSA Hawaii facility only opened in January 2012, replacing an older site located in a nearby World War II-era facility.

The operation is focused on intercepting communications from Asia, and is reported to be also involved in cyberspace monitoring.

Mr Snowden was posted by consultant Booz Allen Hamilton to the Hawaii facility in late March or early April 2013, after first attending training sessions near NSA's Maryland headquarters.

He told his employers in Hawaii after a few weeks he needed time off because of health problems but then disappeared and turned up several weeks later in Hong Kong.

He then flew to Russia where he has been granted temporary political asylum. 

Another US official told Reuters that US agencies were still not positive they knew the details of all the material which Mr Snowden had downloaded and turned over to journalists.