Intelligence agencies have detained three men in Karachi over their alleged involvement with Ajmal Kasab, the lone surviving gunman of the November 2008 Mumbai attacks. The agencies took these men into custody from different areas of Karachi in connection with their alleged affiliation with Kasab, said an official. They were taken to Islamabad and an investigation was in progress. The official said that the arrests were made by the Federal Investigation Agency (FIA) in collaboration with other intelligence agencies. He said that the FIA was mainly carrying out investigation into the dossier provided to Pakistan by Indian about the Mumbai terrorist attack. The official said that any Pakistani national found involved in the incident would be tried in Pakistan and would not be handed over to India or any other country. He said that Pakistan's judicial system was foolproof to punish the guilty. He said nobody could be tried on mere hearsay.