The body was found in a lagoon near a house rented by two Russian men believed to be linked to the disappearance of Alexey Slabinskiy, the Phuket Gazette reported.
Police are now searching for the two men who had rented the house in Soi Koktanode in Cherng Talay: Oleksandr Boychuk, 44, and Aleksandr Novichkov, 58.
Forty officers and sniffer dogs brought in from Nakhon Si Thammarat searched the area after police received a report about the body, Provincial Police Commander Ong-art Phiwruangnont told the Gazette.
"We believe the body is that of Mr Salbinskiy as the sniffer dogs found the remains while searching the area using the scent from Mr Salbinskiy’s belongings," he said.
Mr Slabinskiy’s sister, Tatiana Novoselova, and her husband Sergei Luklanov had offered 500,000 baht for information leading to the arrest of the kidnappers.
Mr Slabinskiy disappeared along with his girlfriend, Iana Strizheus, on March 7. The couple had called relatives in Russia that day to tell them that they had been kidnapped and needed money.
Ms Strizheus was later discovered injured in a hotel room. Four days later, Mr Slabinskiy’s phone was used in Chalong, but he was nowhere to be found.