The Centre on Monday sounded a high alert in Mumbai, Kolkata and Delhi following intelligence inputs that Taliban-trained ‘fidayeen’ (suicide terror squads) may have sneaked in to carry out strikes at vital installations.

Highly placed sources in the Home Ministry said nuclear installations, including the Bhaba Atomic Research Centre at Trombay, the Bombay Stock Exchange in Mumbai and the American Consulate in Kolkata were high on the radar of the 'fidayeen' squads.

The sources said attacks could also be mounted in the Rashtriya Swayamsevak Sangh headquarters in Nagpur, the Kolkata port and some key defence establishments. According to Intelligence inputs, the World Cup Hockey to be held in Delhi in February and some civilian targets in Gujarat could also be on the hit list of the squads that sneaked into the country with the help of the Lashkar-e-Taiba.