Security firm G4S has apologised for the behaviour of staff at a young offender unit after an undercover BBC investigation found evidence of mistreatment of children being held there. A senior director said he was "appalled" after the airing of a Panorama programme tonight which secretly filmed at Medway Secure Training Centre in Rochester. Seven members of staff at the unit have already been suspended amid allegations of abuse and mistreatment of youngsters. Paul Cook, managing director of G4S children's services, said: "We are appalled by the behaviour of certain members of staff at Medway Secure Training Centre shown in the programme and I would like to apologise personally to any young people involved in these incidents."The wellbeing, safety and care of the young people at Medway is our primary objective and we are shocked that any member of staff would behave in this way. "There is no place for the conduct shown in the programme within any of our Secure Training Centres and it will not be tolerated."