ISTANBUL (AP) — The trial against 16 people accused of terror charges and organizing anti-government protests in 2013 has begun in Turkey as rights groups say the allegations are baseless.

The trial is taking place Monday and Tuesday in a prison complex on Istanbul's outskirts. The 657-page indictment claims the defendants "attempted to overthrow the government."

The protests began in 2013 to protect Gezi park in central Istanbul but quickly transformed to wider demonstrations across Turkey to oppose the government. Police used tear gas and water cannons to disperse mostly peaceful protesters.

Prominent civil society figure Osman Kavala has been in pre-trial detention for 19 months and Yigit Aksakoglu, who works for an early childhood education foundation, for seven months.

Human Rights Watch called the charges "bogus."