Some of the people who spoke to ITV News about alleged security breaches by G4S staff were sacked by the G4S and have tribunal cases against the company.
The man in charge of the operation, the G4S Managing Director of Global Events, Ian Horseman Sewell, rejected all their claims:
"At no point is there any evidence that dogs that have been trained to detect substances other than explosives have been used to try to detect explosives."
More top news
Pope Francis slipped out of the Vatican to make a surprise visit to an optician's to get a new pair of glasses.
An extra hour a day of TV, internet or computer gaming could reduce GCSE success by two grades, research claims.
David Cameron is expected to announce a new plan that will see Britain take in thousands more Syrian refugees.