Fear of a surge in Omicron cases has led to the cancellation of all events to mark the New Year planned for Bangkok by City Hall, and the private sector is being urged to follow suit.
Bangkok deputy governor Kriengyos Sudlapha announced the decision on Thursday.
Mr Kriengyos said the Bangkok Metropolitan Administration (BMA) took into account the rapid rise in new infections linked to the Omicron variant of the coronavirus, and advice from the World Health Organisation that countries should put New Year holiday celebrations on hold.
City Hall had planned an overnight prayer ceremony to count down the end of the year, and a morning alms-offering to monks on New Year's Day at its Larn Khon Muang headquarters, near the Giant Swing.
They were now cancelled.
District offices had also planned religious ceremonies to greet the New Year. They, and any other events, were cancelled.
At least two major New Year countdown parties are planned in Bangkok - at Iconsiam and CentralWorld shopping centres.
Mr Kriengyos said all private gatherings already approved by City Hall were still allowed, but he urged organisers to follow in the steps of the BMA decision.
"We will not ban those events, but we are seeking their cooperation in cancelling them. If the events are not cancelled [by the organisers], the guidelines set by the Public Health Ministry must be strictly followed," he said.
He strongly advised people to avoid large gatherings during the holiday period, to lessen the risk of Covid-19 infection.
There have been 104 confirmed cases of infection with the Omicron variant since the first transmission in Thailand was detected on Dec 6.