By The Nation
Police said the quarrel broke out after the French tourist reprimanded the Thai, identified by police as Seri Rodleang, for urinating into a canal. Seri then returned with a knife and attacked the Frenchman.
The victim, named as Leo Alexander Achille, 24, tried to stop the fight but was stabbed.
The police were alerted at 2.30am and Seri was arrested soon after.
Achille was staying at the Flapping Duck guesthouse behind the Phra Sumain Fort on Bang Lamphu road in Samsen Nai sub-distirct.
His Thai friend, Malieen Promnat, said the Swiss tourist heard Seri and the French tourist shouting loudly on the bridge across a canal in front of the guesthouse at 2am and went out to stop them.
Seri later came back with a knife and threatened the French tourist.
Achille once again tried to stop the fight but was stabbed.
Police arrested Seri as he was fleeing towards Phra Arthit Road.