A leading mental health charity has called for an end to the use of custody cells to deal with the mentally ill.
Figures from the National Police Chiefs Council show 336 mental health detentions un police cells in Wales during 2015-16, according to information obtained by the BBC.
This represents a significant fall from 541 the year before, however, Mind Cymru insist use of the measure needs to stop.
Director of Mind Cymru Sara Moseley said: “When you're in a mental health crisis, you may become frustrated frightened and extremely distressed.
"Your behaviour could be perceived as aggressive and threatening to others, but you desperately need support and compassion.
“Being held in a police cell and effectively treated like a criminal only makes things worse.
"In England, police forces are showing us what is possible. If Merseyside and Hertfordshire police forces can entirely avoid detaining vulnerable people in police cells, so can any other police force area, including here in Wales.”
Welsh forces say the number of people detained who have mental health problems is falling.
South Wales Police & Crime Commissioner Alun Michael claimed the issue was not a policing one but more to do with public service policy.
He said: “At its heart this is not a policing problem but a problem for the public service as a whole, and all too often people end up in a police station or custody cell because there is no other place of safety or treatment available at the time of crisis.”
The Home Office pointed out figures had halved across the country over the last year but admitted there is work still to be done.
A spokeswoman said: “We are committed to ensuring those in mental health crisis get compassionate care - and that no one is taken to a cell when they have committed no crime and solely because there is no alternative safe place for them.”
The Policing and Crime Bill, currently on its way through The Lords, sets out plans to prohibit the use of cells for under 18s with mental health problems as well as guidelines to ensure cells are only used for adults in exceptional circumstances.