Police in Hampshire were called out to nearly 10,000 incidents involving mental health last year.
Data obtained by the think tank Parliament Street show officers attended 9.597 incidents last year where the call-out referenced a person with a mental health condition.
Of the 28 UK forces which responded to Freedom of Information requests, Hampshire Constabulary had the 11th highest number of incidents.
There were 296,773 incidents involving people with mental health issues in the UK last year.
South Wales Police had the highest total of any force with 38,712.
Danny Bowman, mental health spokesman for Parliament Street, 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: ‘Mental health is core police business.’
He said police officers are often the first people to come into contact with “people in mental health crisis” and it was important they had the right support, including from NHS mental health services, to ensure people get the help they need.
He called for further investment to help people before they reach crisis point, adding: ‘Getting people the right help as early as possible means people can manage their mental health, are less likely to end up in crisis and, ultimately, will reduce pressure on all emergency 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 £30 million 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.’