Yes, a government employee (Public Servant) in India can be a member of an NGO (Non-Governmental Organization) as long as the activities of the NGO do not conflict with the employee's official duties and responsibilities. It is a Constitutional Right as long as the objects of such NGO are NOT against to the interests of the sovereignty and integrity of India or public order.
As per CENTRAL CIVIL SERVICES (CONDUCT) RULES, 1964 Rule 15(2)
A Government servant may, WITHOUT the previous sanction of Government--
(a) undertake honorary work of a social or charitable nature, or
(b) undertake occasional work of a literary, artistic or scientific character, or
(c) …………….
(d) take part in the registration, promotion or management (not involving the holding of an elective office) of a literary, scientific or charitable society or of a club or similar organisation, the aims or objects of which relate to promotion of sports, cultural or recreational activities, registered under the Societies Registration Act, 1860 (21 of 1860) or any other law for the time being in force, or
(e) ………..
ANDHRA PRADESH & TELANGANA
As per rule 3-A of The Andhra Pradesh Civil Services (Conduct) Rules, 1964. (Joining of association by Government employees):
A Government employee may join, or continue to be a member of, an association the object or activities of which are NOT prejudicial to the interests of the sovereignty and integrity of India or public order.
As per Rule 12 of The Andhra Pradesh Civil Services (Conduct) Rules, 1964
A Government employee (Public Servant) may, without sanction of Government, participate and undertake honorary work of a special or charitable nature subject to the condition that such work does not interfere with his official duties.
Note: For further information/clarifications and exceptions, if any, please contact Citizen Force Legal Division.