The government has asked state agencies and private companies to allow staff to work from home for at least 14 days as Omicron infections soared to more than 1,500 cases nationwide as of Jan 1.

Despite the surge, the situation remains under control without any severe cases caused by the new variant, health authorities said.

Prime Minister Prayut Chan-o-cha instructed state agencies to monitor the Omicron situation closely to prevent any more major clusters of Omicron infections.

He said those who had returned to Bangkok from the provinces via the Mor Chit bus terminal and Hua Lamphong railway station can get antigen tests free of charge.

Dr Kiattiphum Wongrajit, permanent secretary for public health, said Omicron infections have increased as predicted, though there have been no severe cases.

''Generally, patients are concerned about the worst effects such as deaths if they get infected. But as long as infected patients have mild or no symptoms and develop immunity, this should be okay,'' he said.

"In summary, the Omicron variant is spreading. But it has not caused any severe symptoms yet and remains under control," he said.