In a statement, the group Front Line Defenders, asked the government to ensure that human rights activists are able to carry out their legitimate activities without fear of reprisals and free of all restrictions.
"Front Line Defenders strongly condemns the charges brought against Poonam Agarwal, which it believes are solely motivated by her legitimate and peaceful activities in the defence of human rights in India," the group said.
"Immediately drop all charges against Poonam Agarwal as it believes that they are solely motivated by her legitimate and peaceful work in defence of human rights," the group urged the Indian government.
Nashik Police has registered the case against Agarwal under Sections 3 (spying) and 7 (interfering with officers of the police or members of the armed forces of Union) of the OSA after a complaint from Army officials.
Mathew (33) was found hanging from the ceiling of a room in an abandoned barrack in Deolali cantonment here on March 2.