BANGKOK, Thailand (CNN) -- A Thai judge fined dozens of Rohingya refugees from Myanmar who pleaded guilty Wednesday to charges of illegal entry after escaping from their own country a month ago -- amid allegations that other Rohingya have been dumped at sea by the Thai army.

Male refugees show scars they say were caused by beatings at the hands of the Myanmar navy.

The Ranong Provincial Court judge ordered each of the 66 ethnic Muslim refugees to pay 1,000 Thai baht (less than $30). He imposed the fines via a closed-circuit television link to Ranong Provincial Prison, where the refugees will continue to be held until they can pay the court.

Twelve additional refugees, all teenagers, were being detained at a police station and are exempt from prosecution.

The 78 refugees will be handed over on January 31 to immigration police, who will deport them. It is unclear where they will be sent.

The refugees arrived by boat on the Thai shore, and Thai police said many had severe burns from a fire that broke out on board their craft after it left neighboring Myanmar, also known as Burma.

Members of Myanmar's Rohingya minority have been fleeing the country for years, saying they are persecuted by its military government.

One refugee, who called himself Mohamed, told CNN that their boat had been at sea for a month, and that Myanmar's military had detained and attacked them before setting their boat on fire.

The refugees are unwelcome in Thailand, where authorities say about 20,000 have settled illegally.

Other boatloads of Rohingya have allegedly been set adrift after being towed out to sea by Thai authorities.

A recent CNN investigation found evidence of such activity. Photos obtained by CNN include one that shows the Thai army towing a boatload of some 190 refugees. Watch Dan Rivers' BackStory on the investigation »

CNN also interviewed a refugee who said he was one of the few who had survived after a group of six rickety boats was towed back to sea and abandoned by Thai authorities earlier this month.

The Thai government has launched an inquiry. The Thai army has denied the allegations.

But after extensive questioning by CNN, one source in the Thai military confirmed that the Thai army was operating a dump-at-sea policy.

The source defended it, saying that each boatload of refugees is given sufficient supplies of food and water.

That source said Thai villagers had become afraid of the hundreds of Rohingya arriving each month, and they had accused the refugees of stealing their property and threatening them.

The Thai government has said that "there is no reasonable ground to believe" that the Rohingya are fleeing Myanmar because of persecution.

"Their profile and their seasonal travel further support the picture that they are illegal migrants, and not those requiring international protection," the Foreign Ministry said in a statement issued Tuesday.

One of the refugees who came ashore Tuesday said they will be killed if returned to Myanmar because of their minority status. He said the Rohingya are stateless because they lack bribe money to obtain identification cards in Myanmar.

In Tuesday's statement, the Thai government said it deals with all illegal migrants in accordance with its laws and international guidelines.

It said "basic humanitarian needs" such as food and water are met among the migrants before they are returned home. Their boats also are fixed, officials said.

The Thai government said that "accepting those arriving in an irregular manner would simply encourage new arrivals."

The government denied media reports alleging that Thai authorities mistreat the illegal migrants and intentionally damage their boats.

CNN's Dan Rivers and Kocha Olarn contributed to this report.

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