More than 100 people have been arrested in Thailand on charges of lese majeste since the military seized power in a coup d'etat in May 2014, activist groups said Monday.

Article 112 of Thailand's criminal code says anyone who defames, insults or threatens the King, the Queen, the heir-apparent or the regent will be punished with 3-15 years in prison for each of these crimes.

The arrest of six people in late April elevates the number of those that were detained and accused of lese majeste to 105 since the military took power, according to the International Federation for Human Rights (FIDH) and the Thai group iLaw.

Of that figure, 49 have been sentenced to up to 30 years in prison and another 64 are in custody awaiting trials.

The figure multiplies the cases prior to the coup, when six people were imprisoned for this crime.

Of the total of the arrested, 81 were for expressing opinions, mainly on social networks, and the remaining cases are related to individuals who were arrested for claiming ties to the royal family for personal gain.

"In less than three years, the military junta has generated a surge in the number of political prisoners detained under lèse-majesté by abusing a draconian law that is inconsistent with Thailand's international obligations," said FIDH President Dimitris Christopoulos.

iLaw Executive Director Jon Ungpakorn said that lese majeste defendants are rarely granted bail and have to spend years in prison fighting their cases, and called Thailand's justice system a "mockery of justice."

"Many of those arrested are democracy activists and outspoken critics of the military regime. In some instances, they were kidnapped from their homes by military officers and interrogated in secret for several days in military camps before being formally charged," Ungpakorn said.

The UN Human Rights Committee also expressed concern over the "extreme sentencing practices" for those found guilty of lese majeste and urged the Thai authorities to reform Article 112 and respect freedom of expression.