The Public Health Ministry has raised its Covid-19 alert to Level 4 following a sharp increase in Omicron variant infections nationwide.

However, the Centre for Covid-19 Situation Administration (CCSA) said that more lockdowns were unlikely.

The raised alert level came as the number of new infections, severe cases and deaths continue to rise, with authorities noting an increasing risk of infection among family members and close acquaintances as a result of activities such as dining out, playing sports, and attending wedding and funeral ceremonies.

People from at-risk groups -- including the elderly, those with underlying health conditions and the unvaccinated -- continue to account for most Covid-related deaths.

Under the new alert, people are encouraged to work from home, avoid non-essential inter-provincial travel, suspend overseas trips, close at-risk venues and avoid large gatherings.

The ministry had raised the alert to Level 4 in some red-zone provinces early last month. The alert will now apply to all provinces nationwide.

CCSA spokeswoman Apisamai Srirangson on Monday said from Wednesday, the CCSA will focus on the number of deaths and severe cases, rather than the spike in new cases.

"While the CCSA is unlikely to bring back lockdowns, Thailand still cannot afford to relax virus curbs in the same way as other countries have done. We have to come up with our own approach," Dr Apisamai said.