Activist Venkatesh Nayak had asked for a report on the massacre, alleging it violated the rights of the personnel.
The CRPF quoted clauses under the RTI Act, which exempt it from making disclosures in this case.
In one of their deadliest ambush in years, about 300 Naxals opened fire on a platoon of CRPF in Chhattisgarh's Sukma on April 24.
Twenty-five personnel died and six were injured.
Afterwards, the Centre approved aggressive offensive against Naxals. It also issued a hit-list of the top leadership.
In the last seven years, about 200 security personnel have died in Maoist attacks in Chhattisgarh.
"There appears to be no violations of human rights, and facts of the case do not attract allegations of corruption. Moreover, your application doesn't make any reference to such allegations. Hence, (we) aren't liable to provide any information in this regard under RTI Act-2005."
It added the enquiry report contained classified security issues, and so couldn't be shared as it might affect CRPF's strategy.
However, Nayak called the response an "injustice" to CRPF's own personnel. "Clearly, the murderous attack in April by left-wing extremist groups amounts to violation of their human rights by non-state actors. By denying this reality, the CRPF may be doing injustice to its own personnel."
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