All Indian carriers will be on a high alert on Sunday in the wake of a bomb threat.

Though an e-mail threatening that a bomb will be placed on a flight — received by Air India a week ago — did not give any specific information, the Bureau of Civil Aviation Security (BCAS) has issued an advisory to all airlines.

Air India spokesperson Jeetendra Bhargav said the content of the e-mail was vague. It was received in New Delhi, following which it was passed on to the BCAS.

“There is no specific input, but we are cautious,” said Central Industrial Security Force (CISF) senior commandant G S Negi in Mumbai. “There will be secondary ladder-point checks tomorrow besides thorough scrutiny of passengers’ cabin baggage.”

While the e-mail mentioned Air India as a possible target, with Air India and Indian Airlines having merged, the alert has been sounded for the entire AI-IA fleet as well as other airlines. Security has also been beefed up at all establishments of the airline.

The airline had received a similar e-mail in April, threatening to blow up its headquarters at Nariman Point in Mumbai.