Three journalists and two activists who fled from Myanmar are on trial in Thailand on charges of illegally entering the country.
If found guilty they are likely to be deported back to Myanmar, where they say their lives would be in danger.
Following the military coup on 1 February, dozens of journalists have been arrested and charged in Myanmar.
Security forces have killed more than 700 people and detained thousands.
There have since been reports of detainees being tortured while in custody, with some dying from their injuries.
The group of five, who have not yet been named by Thai authorities, were detained by police in the city of Chiang Mai on Sunday.
They are three journalists from well-known broadcaster Democratic Voice of Burma (DVB), and two activists. Charged with illegal entry into Thailand, they could face immediate deportation if found guilty.
Like many media organisations, DVB has been banned from operating inside Myanmar, also referred to as Burma.
The broadcaster said it “strongly urges the Thai authorities to not deport them back to Burma, as their life will be in serious danger if they were to return”.
It also urged the United National High Commissioner for Refugees in Bangkok and the international community to help.