Airports in Tamil Nadu and Kerala were put on high alert on Tuesday following a bomb scare, which turned out to be hoax.     

Airport sources in Chennai said that an anonymous caller rang up a police station at Mangalore, stating that 'a human bomb' travelling in the Doha-Chennai-Qatar Airways flight will blow up after the flight landed in the city.

The Karnataka Director General of Police, who was informed about the call, alerted his Tamil Nadu counterpart, D Mukherjee. Mukherjee passed on the information to Chennai airport officials following which bomb disposal squads were put on alert.

A team, along with sniffer dogs, frisked all 177 people on board and combed the aircraft for nearly two hours and found that the call was hoax.

Following the call, security was beefed up at Chennai, Madurai, Coimbatore and Tiruchirapalli airports, sources said.     

A Thiruvanathapuram report said security was tightened at three international airports in Kerala following the call.

Security personnel at Thiruvanthanpuram, Kochi and Kozhikode airports thoroughly searched some flights, which arrived from the Gulf sector and found they were safe, airport sources said

The aircraft and luggage of passengers were also checked before the flights were allowed to proceed.

The flights searched were Doha-Thiruvanthapuram-Kozhikode service of Air India Express and Qatar Airways' Doha Thiruvananthapuram Doha flights, airport sources said.

The checks, however, did not cause any inordinate delay in the departure of the flights, the sources said.