"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.