Mental health police incidents at 'shocking' levels
Figures suggest "shocking" numbers of incidents involving people with mental health issues are handled by police.
England and Northern Ireland faced nearly 240,000 such incidents in 2016, figures show.
Freedom of Information requests found Nottinghamshire recording the most, with 19,973 and the Police Service of Northern Ireland next at 19,668.
Parliament Street, which studies political issues, called for greater investment in mental health services.
There were 239,388 incidents reported but there was wide variation, with Lincolnshire Police recording the least at 2,512.
Parliament Street's mental health spokesman, Danny Bowman, said: "These findings reveal the shocking numbers of mental health issues currently being dealt with by police forces across the country.
"It's time to recognise that Britain needs a better funded strategic plan to ensure people who are suffering with mental health problems are properly cared for by specialist health services."
Paul Farmer, chief executive of the mental health charity Mind, said it was important vulnerable people had the right support, including from NHS mental health services,
A government spokesman said: "People experiencing mental health crisis need the right care in the right place, not a police cell.
"We're investing £30m in providing more alternative places of safety, have more than halved the number of people detained under a mental health section in a police cell in the last year and are entirely banning the use of police stations for this purpose for under 18s."
Sgt Anthony Horsnall of Nottinghamshire Police said mental health was identified as a priority in the Police and Crime Plan.
"We have reviewed and made significant improvements in the way that we record police incidents that are linked to mental health and this is reflected in the data.
"We have made significant improvements in the way we deal with mental health and have excellent relationships with our partners including Nottinghamshire Healthcare NHS Foundation Trust," he said.