Two-thirds of police and community support officers (PCSOs) have received little or no training to guard scenes of crime, a new report has revealed.
Unison warned this could put vital evidence at risk and has called for a review.
Its study found PCSOs were often left on their own to protect serious crime scenes for many hours without access to a toilet, food or water.
Unison criticised police forces for sending PCSOs out alone when they know staff have limited powers.
General secretary Dave Prentis said: ‘PCSOs do a valuable job, often keeping watch at serious crime scenes so that police officers can be elsewhere, trying to apprehend the criminals.
‘Police support staff are committed to their jobs but want to be properly trained and equipped so they know how to deal with suspects returning to the scene to remove any trace of evidence.
‘PCSOs’ welfare must be a top priority, especially when they are out in all weathers, sometimes in remote areas, miles from support.
‘We need an urgent review into the training and support PCSOs get. If criminals are to be brought to justice, police support staff must be given the necessary tools to do the difficult job of keeping communities safe from those who break the law.’