Police are continuing to search for 13-year-old Caitlyn Critchley who has been missing from Westham, near Pevensey, since around 9.30am on Saturday, August 14.
Enquiries are being made in the area and Brighton, Shoreham and Worthing where she has strong links.
Officers have checked all known addresses that Caitlyn may have gone to and are working closely with her family.
They have received information that she may have been in the Sompting area on Monday, but believe there is a good possibility that she may have travelled to London, perhaps with a friend.
Her details and photograph have been circulated to the Met Police and British Transport Police.
DI Rob Morland, who is heading the search for Caitlyn, said: “Caitlyn has gone missing on a number of occasions this year, but has generally been found or returned within a day or so. She has now been gone for five days and given her vulnerability as a 13-year-old, we are concerned.
“We have no information at this stage to suggest her disappearance isn’t voluntary, but her family and friends – especially her mother who Caitlyn speaks to regularly – are extremely worried about her and want to see her back home safe and well.
“If anyone knows where she is or has seen or heard from her over the last few days, please contact 0845 60 70 999 quoting serial 1799 of 14/08.”
Anyone missing from home or anybody who knows where they are can also contact the 24-hour Young Runaway Mentoring Service in East Sussex on 0300 303 1221.