BANGKOK: A Thai court on Tuesday found two men guilty of attacking villagers and human rights activists protesting against a gold mine in what an international rights watchdog called an important verdict for people standing up for communities.

About 150 men, many of them masked and armed, attacked villagers and rights workers blocking a road to a gold mine in the northeastern province of Loei on May 15, 2014.

Many of the villagers, who were protesting against the environmental damage they said the mine caused, were rounded up and some were beaten, they said.

The attackers were not identified at the time while police declined to comment.

Investigators were later able to identify two men, a father and son, the former a retired army officer and the latter a serving one, as being among the attackers.

The two, retired Lieutenant General Poramet Pomnak and his son, Lieutenant Colonel Poramin Pomnak, were found guilty of taking part in the attack and causing bodily harm, the court said in a statement.

Poramin was sentenced to just under three years in prison while Poramet was handed a two-year sentence.

Reuters was unable to contact their lawyer or an army spokesman for comment.

Environmental and right activists have long criticised Thailand for a poor environmental record and a culture of impunity for the rich and powerful.

Well-connected figures including military officers, civil servants and business people, often enjoy special privileges in exploiting resources and protection from scrutiny and prosecution for wrongdoing.

The International Commission of Jurists (ICJ) welcomed the verdict as an important step.

"It establishes that human rights defenders and community activists can't be attacked with impunity," Sam Zarifi, Asia-Pacific director at the ICJ, told Reuters.

"The overwhelming trend in Thailand for community rights defenders remains that of impunity for their attackers. We hope this is the beginning of a new trend."

More than 100 villagers showed up at the Loei Provincial Court to hear the verdict.

"The villagers have received justice but the legal process is not complete," said Sor Rattanamanee Polkla, a lawyer for the community rights activists.

"There were more than two attackers in this case but police have not yet proceeded with a case against the rest."

Thailand has been ruled by a junta since the military took power from an elected, civilian government in a May 2014 coup.

Last month, the junta said all gold mining would be abolished by the end of the year over environmental and health concerns.