The fire that broke out at the Calcutta airport on Wednesday night started at a small room that is used by airlines to store various stationery items, its director C Pattabhi said.

Speaking to PTI on Thursday, he said an investigation has already started to ascertain the exact cause of the fire.

"The small room from where the fire started is used by airlines to store various stationery items regarding the flight departure process," he said.

It is located next to the check-in counters of portal D, he said.

Though there were no problems regarding operations of incoming flights, some flights that were about to depart were delayed because of the fire, Pattabhi said.

The fire broke out at the Netaji Subhas Chandra Bose International Airport around 9.12 pm on Wednesday, leading to chaos and panic among passengers. The fire was doused by 9.40 pm, and check-in services resumed at 10.25 pm, officials said.

No one was injured in the mishap, they said.

Sources said a preliminary report on the incident has already been sent to different agencies concerned.

West Bengal Fire Services Minister Sujit Bose earlier told PTI, "Initially, it seems that some fault related to the air conditioning system caused the fire." Departures of 13 fights were delayed due to the fire, officials said.