Terming Naxals as the biggest terrorists, Chhattisgarh chief minister Raman Singh on Wednesday said there cannot be a "soft line" to deal with Maoists but disfavoured use of air power to combat the menace.

Attributing the recent spur in the Naxal violence to frontal operations by the security forces in the state, Singh favoured a long-term action joint action plan with the Centre to tackle the problem.