A case of the variant was confirmed last week in Sweden and linked to a growing outbreak in Africa, the first sign of its spread outside the continent.
The World Health Organisation declared the recent outbreak of the disease a public health emergency of international concern after the new variant was identified.
Thai authorities on Wednesday said the man confirmed as having mpox had transited in a Middle Eastern country, which they also did not name, before flying on to Thailand.
Thailand has detected 800 cases of mpox Clade 2 since 2022 but so far not detected a case of the Clade 1 or Clade 1b variants.
Singapore’s health ministry said it had detected 13 cases of mpox Clade 2 infections this year.
To date, all mpox infections in the city state have been the “less severe” Clade 2 infections, the ministry said in a bulletin on Thursday.
The government said it was monitoring the global situation closely.
The health ministry said that as a precaution, it will from Friday screen the temperatures of travellers arriving at Changi and Seletar airports from places exposed to the risk of mpox outbreaks.