The government is monitoring two new Omicron subvariants in Europe as Thailand prepares for an influx of international arrivals from next month when entry rules are eased further.

Government spokesman Thanakorn Wangboonkongchana said the Public Health Ministry will monitor the Covid-19 situation in Europe after cases of the two subvariants -- BA.4 and BA.5 -- were detected in countries such as Portugal, the UK, Austria, the Netherlands, France and Germany.

State agencies have also been instructed to plan ahead to deal with the expected surge in foreign arrivals after the Thailand Pass registration requirement is revoked on July 1, the spokesman said.

The Department of Medical Sciences (DMSC) said people should not jump to conclusions about the new subvariants, to avoid causing public panic.

The DMSC is studying the variants to learn more about them.

Health authorities have collected samples of the subvariants, though it may take up to five weeks to determine how they differ from previous strains.

According to the Centre for Medical Genomics at Ramathibodi Hospital, Thailand has recorded 49 new cases of the two new Omicron subvariants, which are considered more contagious.

The head of the centre previously said 26 cases of BA.5, 23 cases of BA.4 and 18 cases of BA.2.12.1 had been detected in the kingdom since April.

"Omicron is not the last variant of Covid-19," he said.