The teenager had to be held in police custody for two nights, after Devon and Cornwall force were told there were no hospital beds available anywhere in the UK.
Assistant Chief Constable Paul Netherton took to Twitter to express his frustration with the situation:
@ACC_Operations: We have a 16yr old girl suffering from mental health issues held in police custody. There are no beds available in the uk! #unacceptable
He said he was "very concerned" about the girl's welfare and the impact the situation would have on her, adding:
"A police station and a custody block on a Friday and a Saturday night simply is not a place where a young child should be placed.
"We wouldn't put a criminal in custody for that long, and we certainly don't want to put someone who is suffering from mental health issues in a custody block for that length of time."
An "appropriate" place was eventually found for her at a 'local place of care' on Saturday.
Jonathan Clark is Director of 'Premier Life', which includes Premier Lifeline.
He also used to be a mental health social worker and was regularly asked to assess those in police custody.
On hearing about this case, he expressed concern that she wasn't in the hands of mental health professionals in the first place, explaining:
"Usually the police only get involved if the person is causing some form of disruption or acting in a somewhat strange way in a public place.
"And at that point they're often seen as a nuisance, a problem, rather than someone with a mental health problem.
"In practice, they should not end up in a police cell. They should be in a place of safety provided by health or social services, where that person can then be assessed."
Premier Lifeline is the National Christian Helpline. It is a confidential telephone helpline offering a listening ear along with emotional and spiritual support from a Christian perspective and prayer.
It was recently re-awarded the quality standard mark from the Mental Health Helplines Partnership.
Premier Lifeline operates 15 hours per day, 7 days a week throughout the year.
Call 0300 111 0101 or visit http://www.premier.org.uk/Premier-Lifeline/
Listen to the interview in full with Premier's Antony Bushfield and Jonathan Clark.