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An international rights group accused Thailand's army chief on Thursday of interfering with investigations into deadly political unrest that paralyzed the capital two years ago.

New York-based Human Rights Watch issued a statement urging army chief Prayuth Chan-ocha to stay out of the probe into the deaths of more than 90 people killed during a nine-week anti-government protest in Bangkok that ended with a military crackdown. The group accused Prayuth of trying to intimidate investigators and critics in an attempt to halt criticism of the military.

Prayuth has denied any army abuses during the 2010 protest and crackdown, which also saw more than 2,000 people injured and buildings across the city set ablaze. Last week, he told the Justice Ministry's Department of Special Investigation to stop accusing soldiers of having killed protesters and not to report publicly on its findings.

"Abuses by soldiers took place in full view of the Thai public and the world's media, yet the Thai army chief is now trying to intimidate investigators and critics into silence," Brad Adams, Human Rights Watch's Asia director, said in the statement.

Those killed in the protests and clashes with the military included protesters, journalists, medics, police and soldiers. During the final days of the protest, heavily armed soldiers were seen firing their weapons in central Bangkok, and some areas of the capital were listed by the government as "live fire zones" in which anyone entering risked being shot.

Supporters of the military and the government of then Prime Minister Abhisit Vejjajiva have pinned the blame for most of the deaths on armed members of the protest group.

Prayuth has denied that the army deployed snipers during the crackdown — a claim Adams called "ludicrous." The rights group cited photographs and videos of soldiers on skyscraper rooftops with telescopic rifles aimed at street protests below.

Prayuth also ordered an army legal officer last week to file a defamation complaint against a Canadian lawyer representing the protesters — members of Thailand's so-called Red Shirt movement — who alleged in a speech that the army committed brutality against demonstrators.

"Instead of going after critics, (Prayuth) should be ensuring accountability within his ranks," Adams said.

The army spokesman did not return several calls seeking comment Thursday.

Human Rights Watch also expressed concern that current Prime Minister Yingluck Shinawatra's government appeared to be siding with the military, rather than holding it accountable.

In response to Prayuth's comments, a deputy prime minister ordered the Department of Special Investigation chief to stop talking publicly about the investigations and to apologize to the army chief.

Not one soldier or official has been charged in connection with the crackdown, which was ordered by Abhisit's government and led by Prayuth.

Many of the Red Shirt protesters involved in the 2010 demonstrations were supporters of Yingluck's brother, former Prime Minister Thaksin Shinawatra, who was ousted in a 2006 military coup and lives in exile. Some Red Shirts have accused Yingluck of abandoning their cause despite riding their support to a massive electoral victory last year.