Police are searching for teenager Amir Taibi, who is missing from Chichester, the force said
According to police the 17-year-old was last seen in the area on September 18, and it is believed he may have travelled to Cambridge.
Amir is described by police as Asian, about 5ft 11in, of slim build, with cropped afro-style hair and facial hair.
He was last seen wearing a camouflaged jacket, dark trousers and dark trainers, and carrying a Union Jack rucksack.
Anyone with any knowledge of his whereabouts is asked to report it online or call police on 101, quoting serial 809 of 18/09.
Alternatively, people can visit the Crimestoppers website or contact the independent charity anonymously on 0800 555 111.