Security at the Chhatrapathi Shivaji International Airport in Mumbai was beefed up on Thursday following an alert from the city police. While in the domestic airport security was as usual, at the International terminal additional reinforcements have been made. <br/> <br/>Mumbai Police sources said the alert had been sounded at the airport fearing a possible hijack attempt to secure the release of lone surviving terrorist Ajmal Kasab, sentenced to death in connection with the 26/11 attack on the city.<br/>