Police believe a missing teenage girl and a 21-year-old man may have been in the London area in the past few days.
The search is continuing for Holly Whitmore, 16, and Brandon Cunningham.
A police spokesman said: “Efforts are continuing to locate Holly and Brandon and officers would appeal directly to them to attend their nearest police station in order to confirm their welfare.”
Brandon went missing from his home in Corby on Sunday, September 2, and Holly went missing from Rushden on Saturday, September 8.
Brandon is white, 5ft 8ins tall and slim, with blue eyes and brown hair.
Holly is white, 5ft 3ins tall and slim, with brown eyes and dark hair which has been dyed blonde.
Anyone who thinks they may have seen Brandon or Holly, or who has information about their whereabouts, is asked to call the police on 101, or 999 in an emergency.