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.
Since the military coup on 1 February, dozens of journalists have been arrested and charged in Myanmar.
More than 700 people have been killed by security forces and thousands have been detained.
There have since been multiple reports of detainees being tortured while in custody, with some dying from their injuries.
The group of five, who have yet to be 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”.
DVB also urged the United National High Commissioner for Refugees in Bangkok and the international community to help.
With a common border stretching more than 2,000km (1,200 miles), Thailand is a natural haven for those fleeing violence and repression in Myanmar.
Many dissident media organisations based themselves in Thailand during the long periods of military rule in the past, and since the coup in February dozens of journalists and activists have once again crossed the border to escape arrest.
Until now the Thai authorities have mostly turned a blind eye to these fugitives, many without passports or visas.
The country has accommodated large numbers of refugees in the past, often for many years.
But it has not signed the United Nations Convention and Protocol on Refugees, and has at times deported groups of them even when they faced almost certain arrest, or worse, at the hands of their own governments.
The Foreign Correspondents Club of Thailand also called for the five to be granted to the right to remain in the country, saying they would face “certain arrest and persecution”.
“The world is watching what the Thai authorities do in this important case for press freedom in Myanmar and the region, and for the protection of those fleeing the junta’s brutal crackdown on independent media and civil society.”
According to the FCCT, more than 70 journalists are among the 5,000 people arrested in Myanmar since the February coup, adding that most are in detention at a time when there have been widespread reports of torture and extrajudicial killings.
The Assistance Association for Political Prisoners (AAPP) monitoring group says 50 journalists are still in detention and half of those have been prosecuted. A few foreign journalists have also been arrested.
Myanmar’s military has justified the February takeover by alleging there had been widespread fraud during a general election late last year which had returned elected leader Aung San Suu Kyi and her National League for Democracy party (NLD) to power.
The military promised instead that it would hold “free and fair” elections once the state of emergency is over