A fire broke out in the Air Traffic Control tower at the Chennai airport in the early hours of Tuesday after batteries in a power back-up system burst, airport officials said.

The fire was put out in half an hour, but services were disrupted for some hours. No one was injured in the incident, airport officialssaid.

Fire service personnel rushed to douse the fire, but smoke entered the Area Control Tower, situated on the third floor, through air-conditioning ducts, requiring evacuation of nearly 40 employees.

Four international flights were diverted to Bangalore and one to Hyderabad. Normality was restored around 7.30 a.m., airport officials said.

D. Devaraj, Regional Executive Director, Airports Authority of India, told The Hindu that the batteries were part of the Advanced Surface Movement and Guidance Control System (ASMGCS) housed in the third floor of the ATC tower. Around 2.30 a.m., the batteries, which were recently procured, burst, resulting in the ASMGCS being disrupted.

Other services at the ATC tower were disconnected immediately after the fire broke out.

Mr Devaraj said that soon after the smoke entered the Area Control Centre, nearly 40 staff members were evacuated immediately. However, the authorities were had to break open half a dozen window panes to let out the smoke.

During this period, five international flights – Gulf Air, Qatar Airways and Indigo services from Dubai, and two Air India flights bound for Chennai -- were diverted. While the Indigo flight was diverted to Hyderabad, the rest were directed to Bangalore, he said.

Around 3 a.m. the lighting system at the Tower was restored partially.

Thereafter, they had to exhaust the smoke from the Area Control Centre hall. Operations at the tower were partially restored around 5 a.m. using training simulators located on the first floor. The first flight to depart after resumption of services was a Cathay Pacific service at 5.20 a.m., Mr. Devaraj said.

This was followed by five other flights in the international sector. With the information passed on to the nearby airports, the arrival of several flights to Chennai in the domestic sector was put on hold.

Automation at the ATC tower was partially restored around 7.25 a.m. “This is the first time a fire accident took place the Tower, which disrupted the function as well the landing and taking-off of aircraft,” Mr. Devaraj said. Airport authorities will investigate the mishap.