Police are concerned for the welfare of two missing girls - 14-year-old Sophie McCarron and Eva Sloka, 16.
Sophie, from Folkestone, and Eva Sloka from Westcliffe, Southend, 16, were attending as voluntary patients at The Priory, Ticehurst, when they went missing together on 26 October.
DS Gavin Patch, from Bexhill CID, said: "Sophie is a vulnerable teenager who has mental health issues and is in need of medication. Eva is being treated as vulnerable by Essex Police due to her age and absence from home. I have made extensive enquiries and believe they were seen together in Southend the day after they disappeared. I am liaising with colleagues in Essex and Kent as I believe the two of them are travelling in the South East using public transport. My concern has increased for both of the girls because of the length of time they have been missing and their vulnerability.
"Sophie is white and about 5ft 6in with straight brown hair. When she went missing she was wearing green combat trousers, a dark hoody, black dolly shoes and a woolly hat.
"Eva is described as white, untidy shoulder length orange hair, 5 ft 7in, with pale complexion and brown eyes. We believe she now has a piercing below her bottom lip and may be wearing a Superman hat. At the time of her disappearance she was wearing a long black cardigan, cream boots and tracksuit bottoms.
"Anyone who may see them or knows where they are is asked to contact police on 0845 60 70 999, quoting serial 1528 of 26 October, or the registered charity Crimestoppers on 0800 555 111."