A threat to bomb two Air India flights was on Thursday made by an anonymous dialler, the third straight day when security personnel in the country went into a tizzy over such calls.

"The Air India office at Mumbai received a bomb threat call on Thursday evening," the national carrier said.

The caller allegedly threatened to blow up two Air India flights — AI 945 Chennai-to-Hyderabad and the Chennai-to- Delhi AI 143.

The airline said the call was declared "non-specific" by the bomb threat assessment committee, which advised that all laid-down procedures be followed.

"Air India has stepped up the security measures. All the flights are operating as per schedule," it added.

Following the call, police and airport authorities are taking stock of the situation, officials said at the airport here.

Panic gripped passengers at Delhi’s Indira Gandhi International Airport on Tuesday after the Jet Airways call centre received threats about bombs in five of its aircraft from here, hours after blasts ripped through Brussels airport, killing over 20.

On Wednesday, there was a major security scare at several airports in the country, including the national capital, following a phone call from the US that 11 aircraft of private carrier IndiGo could be in the danger of being blown up.