Nearly 50 Pakistan-trained youths are still holed up in Mumbai and its adjoining areas and are ready to strike any time on the orders of Lashkar-e-Tayiba leaders across the border, police sources have said.

The Mumbai crime branch and the Anti Terrorism Squad have so far busted two modules.

They have also arrested a key Lashkar leader, Faizal Sheikh, instrumental in motivating young Muslims to join the outfit.

Officials who interrogated Faizal Sheikh and two more suspects -- Firoze Ghaswala and Mohammed Chippa, arrested in connection with the Delhi blasts -- told that Faizal and another Lashkar leader Raheel Sheikh were consistently motivating city youths to join training camps in Pakistan.

Since 1996, Faizal and Raheel have sent over 50 persons from Mumbai, Navi Mumbai and Thane region to Pakistan for training, sources said.

So far, the ATS has hit a dead end in its efforts to learn the details of the 'sleeper modules' (as these trained but dormant LeT operatives are called), sources said.

They added that like blasts suspects Tanvir Ansari, Jameer Sheikh and Sohail Sheikh who were reportedly sent to Pakistan by Faizal, it was Raheel who arranged the trip of Ghaswala and Chippa a couple of years ago.

While Ghaswala and Chippa were arrested in Delhi soon after they returned, Ansari, Mumbai police arrested Jameer and Sohail after the July 11 blasts.