Basic rights to freedom of opinion, expression and assembly are at risk, as well as guarantees of protection from arbitrary arrest or detention, it said.
"We remind the authorities of Thailand's obligations under international human rights law in particular the International Covenant on Civil and Political Rights which strictly limit the application of emergency powers," U.N. human rights spokeswoman Ravina Shamdasani said.
"We urge the authorities to take all necessary measures to ensure the fundamental human rights are respected," she said.