A case was registered against six unidentified persons on Friday in connection with the hijack alarm incident involving an Air India flight at the international airport in Thiruvananthapuram.

Police said the case was registered based on a complaint by the Abu Dhabi-Kochi bound flight pilot Rupali Waghmare, who sent the hijack alert in panic after agitated passengers allegedly stormed the cockpit.

In her complaint, which was sent to the state DGP, the pilot claimed she was threatened, manhandled and restrained from moving out for more than five hours, police said.

The case was registered even as Kerala chief minister Oommen Chandy ordered a probe into the incident.

Complaints of passengers against the pilot and also her charges against passengers would be looked into, he said.

Chandy, who had described the incident as a spontaneous reaction, said he has instructed director general of police KS Balasubramaniam to investigate the matter.

Around 200 passengers of an Air India Kochi bound flight from Abu Dhabi protested and some allegedly tried to enter the cockpit after the Kochi bound flight was diverted here due to bad visibility.

Six passengers were detained and questioned by Central Industrial Security Force personnel when the plane landed at Kochi after about a nine hour delay and let off.