Sussex Police said Erin, from Eastbourne, has not been seen since about 9am on Saturday, June 28.
“Erin is 5’3” and has brown straight hair that is curly at the bottom,” a spokesperson for the force said.
"She was last seen wearing a white vest top and grey jogging bottoms.
“She is believed to be using the train network and may be travelling to London.
“If you see Erin or have any information about her whereabouts, please call 101 quoting 1385 of 28/6.”

1. Teenage girl, 12, missing from Eastbourne
Erin. Photo: Sussex Police Photo: Sussex Police
