Kolkata, Apr 26 (IANS): After Trinamool Congress, strongman Anubrata Mandal denied having a passport, the Central Bureau of Investigation (CBI) on Tuesday alerted the Kolkata airport authorities and said that any possible air travel attempt by Mandal via there should immediately be brought to its notice.

The CBI officers have also contacted the Regional Passport Office in Kolkata to verify Mandal's claims of not having any passport.

According to highly-placed CBI sources, on Monday, the central agency had sought from Mandal details about his passport, but he denied having one. For the time being, the agency has procured photocopies of his Aadhaar and PAN cards.

"However, we have alerted the Kolkata airport authorities and have also contacted the Regional Passport Office here to cross-check his claims," said a CBI source on strict condition of anonymity.

According to him, till the time they are clear on when and how they will be able to get Mandal for questioning, he will be kept under surveillance as far as possible.

On Monday afternoon, Mandal gave conditions to the CBI to appear for interrogation. At around 5.30 p.m., his letters reached the offices of CBI's anti-corruption branch (ACB) and special crime branch (SCB), containing the Trinamool Birbhum district President's conditions relating to time and place of his appearance for interrogation.

In the letters to the ACB and SCB, Mandal mentioned that he will be able to appear before the CBI only after May 21. As regards to the place of integration, he insisted that it would be decided only after mutual discussion.

Mandal had been using a medical report as a shield to avoid the CBI. He has also given seven summons from the central probe agency a miss, six of which are pertaining to cattle and coal smuggling cases and one relating to post-poll violence in the state.