Police are growing concerned for Mohammed Khan, 11, last seen in Deptford, south London at around 4pm on Tuesday, November 30.
The boy is from Afghanistan and arrived in the capital less than a month ago with officers saying he will not know his way around the capital.
His first language is Pashto and his English is described as very limited.
Mohammed left the address where he is staying to play football in a nearby park.
When he did not return, the police were called and officers began a search of the area.
A high risk missing person investigation was launched and is ongoing.
Mohammed is 4’11” tall, with short dark hair. When he was last seen he was wearing black jeans, a black puffa jacket and a black hat with a Chicago Bulls logo on.
Acting Detective Inspector Lara Pink, from the South East Missing Persons Unit, said: “As we enter the second night since Mohammed went missing, we are growing increasingly concerned.
“He is in an unfamiliar country and doesn’t speak much English. He has only recently arrived in Deptford and won’t know his way around.
“While we are keeping an open mind, we cannot rule out that Mohammed has come into contact with people who may wish him harm and it is important that anyone with any information about his whereabouts comes forward.”
Anyone who sees Mohammed should call 999, with the reference 7180/01DEC.
Anyone with other information should call police on 101 or Crimestoppers, anonymously, on 0800 555 111.