Three Thai human rights activists have been charged with criminal defamation over a report that detailed alleged systematic torture inside military enclosures in the country's southern provinces. All three denied the charges and were freed Wednesday without having to post bail.

They were freed on the condition they submit detailed testimony to the lead investigator in the case, explaining circumstances around the study they wrote. They have about two months to submit the report so the investigator can decide whether to go ahead with the case, said one the activists' lawyers, Preeda Nakphew from the Cross Cultural Foundation advocacy group.

The charges involve a report the three issued alleging torture by security forces in Thailand's southern provinces, where a Muslim insurgency has lasted more than a decade. If convicted they face up to five years in jail.

Amnesty International has called on Thai authorities to drop the charges and instead investigate the allegations in the report.

The report issued in February described acts of torture in the southern provinces as systematic and said that in spite of complaints and campaigns by victims and rights organizations, "the state has not taken any significant action to prevent and address torture."

Government spokesman Winthai Suvaree said in response to their report that there was no evidence to support the allegations.

The United States voiced concern Wednesday over the decision to file criminal defamation charges against the three activists.

"Such actions create a climate of intimidation and encourage self-censorship, which hampers the ability to effectively address the problems in any society," said Katina Adams, spokeswoman for the State Department's bureau for East Asia and the Pacific.

She said it undermined the positive steps taken by Thailand to address torture, including the introduction of legislation that would criminalize torture and enforced disappearance. She said the U.S. was encouraging the bill's swift passage and implementation.

In a separate case, the niece of an army conscript who was tortured to death by soldiers was released on bail after being arrested on a complaint filed by a military officer over her internet postings. She was taken to the province of Narathiwat, 800 kilometers (500 miles) south of Bangkok late Tuesday night, where she denied the charges. She was let out on bail early Wednesday.

Naritsarawan Kaewnopparat posted photos last year of her uncle's body and information about the torture he endured. She was arrested at her workplace in Bangkok on charges of criminal defamation and violating the Computer Crime Act.

The military officer behind the defamation suit against Naritsarawan was one of the 10 army officers involved in the torture of her uncle.

Military personnel are rarely prosecuted for human rights abuses or other crimes in Thailand, and the military government that seized power in May 2014 has clamped down on free speech.

Naritsarawan won 7 million baht ($200,000) compensation in a malfeasance suit against the army, the defense ministry and the prime minister's office, but the actual perpetrators went unpunished.

The army's own investigation concluded Wichian Puaksorn was tortured by about 10 soldiers as punishment when he tried to run away a second time from his camp in Narathiwat province in 2011. It said a first lieutenant gave the order and that Wichian was kicked, beaten and dragged across concrete; salt was rubbed in his wounds before he was wrapped in a sheet and beaten again.