04/08/2012 12:19 BST

More G4S Embarrassment: Anti-Nuclear Protesters Including 82-Year-Old Nun Breach Nuclear Facility In US

There were more red faces at G4S after the UK-run security firm heavily criticised for its London 2012 preparations allowed three anti-nuclear protesters – including an 82-year-old nun – to breach a facility in the US used for storing enriched uranium.

The incursion – slammed as “outrageous” by one congressional investigator – was made at Y-12 in Oak Ridge, Tennessee, according to The Independent.

The paper reports that the complex is guarded by a subsidiary of G4S called WSI Oak Ridge.

But its ability to safeguard the highly sensitive group of buildings was left in grave doubt after anti-nuclear activists named as Megan Rice, 82, Michael Wallis, 63 and Greg Boertje-Obed, 57 - from Oak Ridge Environmental Peace Alliance - spent two hours inside the grounds, even reaching the outer door of the uranium enrichment storage house.

"It is unbelievable this could happen," Peter Stockton, a former congressional investigator and security consultant to the federal government told The Independent. "The significance is outrageous. If they were terrorists, they could have blown open the door and got inside."

No one from the plant has commented on the drama as yet, but the three intruders face trespassing and vandalism charges, having reportedly daubed slogans on some of the buildings.