The Information Commissioner's Office (ICO) has warned organisations that even temporary workers need data protection training in order to properly prevent against a breach.
Its warning comes following four data breaches at the Great Ormond Street Hospital for Children NHS Foundation Trust which saw letters containing sensitive information about the treatment of five patients being sent to the wrong addresses.
The breaches happened between January 2012 and June 2013, with three of the instances caused by temporary staff who despite being involved with the handling of private information, hadn't received proper data protection training.
"This time of year often coincides with a rise in the number of temporary workers being employed across the UK," said ICO enforcement group manager, Sally Anne Poole.
"However, the temporary nature of their employment doesn't absolve employers of their legal responsibilities for making sure people's information is being looked after correctly," she continued.
"If organisations are employing temporary or agency workers into positions that involve the handling and sending out of personal information then they must make sure these staff have received adequate data protection training," Poole said.
She added that Great Ormond Street is now required to ensure it improves its data protection standards.
"Great Ormond Street Hospital for Children NHS Foundation Trust failed to do this and have now been required to sign an undertaking with our office to improve their practices," Poole concluded