Alina Stefan, from Harehills, was reported missing on Monday, after last being seen on Sunday evening.
Alina, who is Romanian, is believed to be with a boy in his late teens known only as “Faele” or “Faiele," and who is also thought to be Romanian.
He is believed to have been in Leeds on Sunday, London on Monday and Tuesday and in Ipswich today. It is believed Alina is with him.
Detective Inspector James Entwistle, of Leeds District CID, said: “We have been carrying out extensive enquiries to trace Alina and we urgently need to find her and check that she is okay.
“We believe she is with the male shown in the photograph, who we know only as Faele or Faiele.
“We would like to hear from anyone who knows his full identity or who has any information on his or Alina’s current whereabouts.”