This is the dramatic moment a hero tourist saves the life of a blood-covered street seller who was stabbed by a Buddhist monk - to test the power of his lucky amulet.

The hawker was selling 'occult' charms when he began arguing with the monk over their strength last Friday (18/01) afternoon in the popular China Town area of Bangkok, Thailand.

Victim Nai Atchawanit, 30, is sad to have told monk Niwan Phrachakasem, 54, that the lucky amulet around his neck was blessed by higher powers and was so powerful it could repel attacks.

Niwan allegedly said he would disprove it and produced a 12-inch long knife from under his orange robes before slashing at Phra Atchawanit's head and neck.

Shocking footage taken by a passer-by shows how the injured man fell to the ground in a pool of blood, before a brave tourist intervened and held him up to try and stop the blood loss.

With the deranged monk a few yards away holding a knife, the tourist was heard calling for help while many locals hurried by - too afraid to intervene for fear of being attacked themselves.

The English-speaking man, in white t-shirt and orange shorts, has been credited with helping to save the victim's life.

Police arrived on the scene and arrested the knifeman monk who told police that the victim had ''encouraged him to stab him to test the power of his amulet''.