The number of times police have detained someone under the Mental Health Act has risen by nearly a third in Wales over the last five years.
Almost 1,000 people in the last year have been detained under the Mental Health Act by South Wales Police, a figure which includes dozens of children.
An assembly committee has said that better support is needed to avoid a "revolving door" where the same people are repeatedly detained and released.
They said work was needed to find out what was behind the increase.
South Wales Police offers have blamed under-funding of mental health services, which means more time and resources are being spent on helping people in mental health crises.
Figures released by the Home Office show South Wales Police detained a total of 913 people under the Mental Health Act in the 12 months to March. Of that figure 35 of whom were aged under 18.
The total figure was an increase of 14 per cent on the previous year, when 799 people were detained.
Under section 136 of the Mental Health Act, police can detain someone and remove them to a "place of safety" if they appear to have a mental disorder and pose a risk to themselves or somebody else.
Three of the four Welsh Police forces saw a rise, but the committee said poor data meant it was difficult to establish the reasons for this.
An assembly committee said "They called for better monitoring of re-admissions and a greater focus on early intervention to avoid repeat detentions."
Although the numbers of people detained under the Mental Health Act had increased, those being held in police custody has reduced year on year.