The reward has been put up by Region 8 Police, Phuket Police commander Maj Gen Chonasit Wattanavrangkul, and Sombat Atiset, owner of the Katathani Resort, where Mrs Smith was staying when she was stabbed to death in what appears to have been a horrifically botched bag-snatching attempt.
Police also announced that they have witnesses who have provided descriptions of the two men who killed.
The descriptions, along with images from CCTV cameras are being used to produce sketches of the two men wanted by police for the killing.
Police sketch artists have been told to drop everything else, and the sketch is expected to be published within 24 hours.