National Security Advisor M K Narayanan on Wednesday appeared to completely rule out the possibility of Naxals bringing down the helicopter of Andhra Pradesh Chief Minister Y S R Reddy that went missing in the state, saying the ultras did not have such a capability.

He said it was quite possible that a technical snag or a pilot error could have led to the chopper going missing.

"Naxal strike seems extremely improbable. I would almost entirely rule it out. I do not think the Naxalites have the capability to bring down the helicopter," Narayanan said in New Delhi.

Narayanan said the government was determined to continue the search for the helicopter or its wreckage and the Chief Minister, his secretary and personal security officer.

"The search will continue till we get hold of the helicopter or its wreckage and the persons on board the helicopter. We will search tonight and tomorrow morning. I Don't think there is any question of calling off the search," Narayanan said.

Pointing out that the country has been very worried over the safety of the Chief Minister, he said the Centre, apart from the state, had done the utmost to find the helicopter by pressing into service IAF helicopers and aircraft with radars for ground mapping the region.