Hinting banned student Islamic organisation SIMI (Student Islamic Movement of India) could be behind the blast in Hyderabad, the Intelligence Bureau has issued an alert to the airport asking them to increase vigil on the flights coming from Nepal and Bangladesh. According to sources, IB has alerted the Delhi Police too, claiming SIMI's men might carry out attacks at markets and other sensitive installations.

"We have been asked to keep a special check on flights coming from Nepal and Bangladesh. There are inputs that members of SIMI will try to enter from these routes to carry out attacks," a source said.

The CISF, responsible for airport security, has also stepped up vigil. "The intelligence wing has been asked to do profiling of suspicious passengers. We have also asked airlines to conduct Secondary Ladder Point Checking (SLPC)," a senior CISF official said.

The alert has also been forwarded to the Delhi Police and markets, areas such as Chandni Chowk, Connaught Place, Greater Kailash, have been put on high alert.