UP Special Task Force (STF) on Friday, Apr 30 raided a CRPF camp based on a tip-off they received in the wake of the Dantewada Maoist massacre on Apr 6.
Two CRPF personnel identified as Vinod Paswan and Dinesh Singh were arrested following raids in Moradabad, Rampur and Jhansi.
The CRPF jawans have been suspended and a Court of Enquiry has been ordered.
Sources revealed that retired sub-inspector of Provincial Armed Constabulary, identified as Yashodhanad Singh, collected empty shells of bullets fired during the training and replaced them at the main Rampur armoury with live bullets.
Singh later supplied these bullets to Naxals, sources added.
There are no details on the fourth person arrested.
Arms and ammunition recovered during the operation include over 5,000 live cartridges, 16 magazines of INSAS rifles, 0.25 bore guns, SLR and AK 47s along with 245 kg of empty shells.
"We have also recovered large number of arms components, mobile phones and Rs 1.76 lakh in cash," Additional Director General of UP police Brij Lal said in a press conference.
The STF is now questioning the four arrested to get more links into this dangerous nexus.
This comes just a day after the Patna special task force (STF) arrested an arms supplier to Maoists and recovered huge cache of arms and ammunition.