Kamran Siddique, who runs NGO 'Real Cause', threw ink at Ramdev during a press conference at
Constitution Club on Saturday afternoon after the yoga guru refused to answer a question on Batla House encounter.
Siddique, who was beaten up by Ramdev's supporters, was detained from the spot and placed under arrested following a medical examination.
"A case under sections 153 (promoting enmity among communities) and 355 (criminal assault) of Indian Penal Code has been registered against him," a senior police official said. If convicted, he may be imprisonment for upto two years.