The decisions were made at a top-level policy meeting, with the government opting for a compromise between needed tourism revenue and fears of a new COVID-19 outbreak, Bangkok Post reported.
The additional sandbox destinations are three islands in Surat Thani province - Koh Samui, Koh Tao and Koh Phangan - and the entire provinces of Krabi and Phangnga. No date was announced for their addition.
Spokesmanof the Centre for Covid-19 Situation Administration (CCSA) Taweesilp Visanuyothin said the CCSA agreed to prolong the suspension of the Test & Go one-quarantine-night-only entry programme until further notice, with January 15 the last date for all pre-approved arrivals.
About 10,000 people registered with the programme have not yet entered the country, he said.
Test & Go and the sandbox schemes for all destinations except Phuket were all put on hold on December 22, as the government tried to control a spike in coronavirus cases and the arrival of the Omicron variant.
The CCSA kept the status of the eight provinces approved for tourism promotion unchanged, meaning they are allowed to serve alcoholic beverages at eateries until 9pm.
The provinces are Bangkok, Chon Buri, Kanchanaburi, Krabi, Nonthaburi, Pathum Thani, Phangnga and Phuket.
Taweesilp said the CCSA decided to step up public health controls in 69 other provinces. That included a ban on alcoholic drinks in restaurants.