The body of a 51-year-old man from Northern Ireland missing since Tuesday following a quarrel with his Thai girlfriend was found floating in the Kwai Noi River in Sai Yok district of Kanchanaburi on Thursday morning.

The dead man was identified by his Thai girlfriend as Robert Lytle. His body was first seen at around 8.20am on Thursday by employees of a bamboo raft resort. They alerted national park officials and rescuers using two flat-bottomed boats and a jet ski from the Pithak Kan foundation were deployed to the river to find the body, which had been swept away by the strong current.

He was found floating face down in the river, wearing only black boxer shorts. The rescue team towed the body to shore. Pol Capt Somboon Pattrawongwiset, deputy investigation chief at Sai Yok police station, led forensic officials and a hospital doctor to investigate. Tourist police were also sent to the scene.

Lytle's body was found about 30 kilometres downstream from the raft house where he and his girlfriend Supapansa Pornkhunthod, 35, were staying, carried along by the huge volume of water being discharged from Vajiralongkorn dam.

A 51-year-old Robort Lytle and his 35-year-old Thai girlfriend photographed at a popular tourist venue in Kanchanaburi. He went missing on Tuesday and was found dead in the Kwai Noi River on Thursday morning. (Photo by Piyarach Chongcharoen)

Ms Supapansa, of Bangkok’s Suan Luang district, had filed a missing person report with Sai Yok police on Wednesday, saying her boyfriend had disappeared after they'd quarreled at their rented raft house on the Kwai Noi River.

She told police they had travelled by private car from Bangkok for a holiday, checking in to the raft house on Monday. That night, they had a quarrel. She left the room at around 3am on Tuesday morning and stayed with a female employee of the raft house. 

She returned to their room at around 8am, but there was no sign of her companion. When she asked around, people said they had seen him earlier, standing on the room's balcony.

Ms Supapansa then said she had searched for him in vain and finally sought help from Sai Yok National Park officials. A search was launched, but Lytle was not seen again until his body was noticed on Thursday morning.

Police were investigating.