Latest: Police 'closing in' on Istanbul nightclub gunman

Update 1.25pm: Turkish police are closing in on the gunman who killed 39 people at an Istanbul nightclub, a senior official said, insisting his possible whereabouts and contacts had been established.

Turkish deputy prime minister Veysi Kaynak said the gunman who attacked Istanbul's upscale Reina nightclub during New Year's celebrations is most probably from China's Muslim Uighur minority and was a "specially trained member of a (terror) cell".