Maoists had used 27 to 30 kgs of explosives during the attack on May 25.

The initial report by National Investigation Agency (NIA) has revealed that four Congress leaders were involved in the deadly attack on Congress convoy by Maoists on May 25.

Four Congress leaders were in 'constant touch' with Maoists on the fateful day, the report said

The NIA has prepared a 14-page preliminary report on Sukma Maoist attack. It will submit its report on Monday. According to the report, these four Congress leaders gave details about the route diversion to Maoists.

The NIA has got the information after anaylising the call details.

The suspicion over insiders being involved in the attack was first raised by Mahendra Karma's son Deepak, who claims that such a precision strike couldn't have been possible without insider inputs.

Earlier, Madhya Pradesh BJP president Narendra Singh Tomar said that former Chhattisgarh chief minister and Congress leader Ajit Jogi was "apparently" the part of the "conspiracy" behind the Maoist attack on Congress convoy that killed 27 people.

