The finding of XE, a mutant hybrid of the BA.1 and BA.2 variants, was reported by the Center for Medical Genomics, Ramathibodi Hospital, reports the Bangkok Post.
In a post on its Facebook page, the centre said the XE recombinant was found through genomic sequencing of a swab sample taken from a Thai patient.
The XE recombinant is not the Deltacron variant, according to the centre.
The WHO warned on Tuesday that XE could be the most transmissible strain of the new coronavirus although its severity is still being investigated.
Citing information from the WHO, the centre said another new variant, Deltacron, a hybrid of the Delta and Omicron strains, does not spread quickly or cause severe symptoms following the unverified finding of another case via Massarray Genotyping.
Omicron XE was first detected in the United Kingdom on Jan 19 this year and more than 600 sequences were reported and have been confirmed since.
Citing reports from the UK Health Services Agency (UKHSA), the centre said Omicron XE is 10% more transmissible than BA.2 and 43% more transmissible than the original Omicron (B.1.1.529).
It remains to be seen if Omicron XE will become the dominant strain, the centre said.
According to Phylogenetic Assignment of Named Global Outbreak Lineages (Pangolin), there are two recombinants of Delta and BA.1, which are XD and XF, and there are six recombinants of BA.1 and BA.2, which are XE, XG, XH, XJ, XK and XL.
Meanwhile, the country registered 26,840 more COVID-19 cases and 97 new fatalities during the previous 24 hours, the Public Health Ministry announced on Sunday morning.
Yesterday, the country logged there were 28,029 new COVID-19 cases with 96 more deaths, according to the ministry.
The figures did not include 14,229 positive results from antigen tests which would have raised the total to 42,258.
Bangkok continued to report the most daily cases with 3,373, up 23 from the 3,350 announced on Friday, followed by 1,507 in Chon Buri, 1,128 in Nakhon Si Thammarat, 936 in Samut Sakhon, 930 in Samut Prakan, 762 in Songkhla, 735 in Chachoengsao, 688 in Nakhon Pathom, 665 in Ayutthaya, and 652 in Khon Kaen.