Human Rights Watch has called on Thailand's army chief to stop interfering with investigations into the deadly political unrest that paralyzed the capital two years ago.

The rights group said in a statement Thursday that army chief Prayuth Chan-ocha was trying to intimidate investigators and critics in an attempt to halt criticism.

Anti-government "Red Shirt" protesters staged a massive nine-week rally in Bangkok in 2010 that ended with a crackdown by soldiers. At least 90 people were killed and more than 2,000 people injured in the violence.

Prayuth has denied any army abuses and told investigators not to publicly report the probe's findings. His spokesman did not immediately return calls for comment Thursday.

Human Rights Watch also urged the government to hold the military accountable, instead of siding with it.