NEW DELHI: The Enforcement Directorate on Monday told a Delhi court that it will need custodial interrogation of former union minister P Chidambaram and his son Karti in Aricel-Maxis deal case once the ongoing probe abroad brings forth evidence.Special Judge O P Saini extended the protection from arrest to father-son duo till May 30 after the defence cited their pending anticipatory bail petitions, and directed the agency to produce the case file to show what material is being collected.The court was told by Solicitor General Tushar Mehta and senior advocate Sonia Mathur, on behalf the agency, that Karti Chidambaram was not cooperating."We (ED) have sent a Special Joint Director to Singapore and have asked him to expedite the process due to paucity of time. We want to interrogate both the accused in custody after receiving the Letters Rogatory (from UK and Singapore)," the agency told the court.The agency alleged that "Karti keeps filing applications to travel abroad to play tennis and he does not want to cooperate in the investigation".The agency made the submissions after senior advocates Kapil Sibal and A M Singhvi, appearing for Chidambarams, requested the court to grant them anticipatory bail, accusing the agency of delaying the matter.After the agency sought more time to argue on Chidambarams' pending anticipatory bail applications, the defence counsel urged the court to extend the interim relief, which was allowed by the court after the ED as well the CBI did not oppose the request.While seeking anticipatory bail, Sibal said, "We are deeply prejudiced and we are in public life. We are entitled to bail. Every time the same prayer is made (by agencies). We get no chance to reply."CBI has only interrogated once since 2014. Is this fair on the part of prosecution? I say grant us (Chidambarams) the bail, and if they (ED and CBI) come across something, we are available. This is the arrogance on the part of the prosecution."At this, the court asked the agencies how much time they required to argue on the anticipatory bail applications."We will send someone again to UK and Singapore and send a message to expedite," the SG said.A team of lawyers including advocates N K Matta, Nitesh Rana, A R Aditya and Noor Rampal appeared for ED in the case.The case relates to alleged irregularities in grant of Foreign Investment Promotion Board (FIPB) approval in the Aircel-Maxis deal.The father-son duo had filed anticipatory bail applications through advocates P K Dubey and Arshdeep Singh, claiming that they were afraid of arrest in both the cases being probed by the ED and the CBI.Their protection from arrest has been extended from time to time.Chidambaram and Karti were named in the charge sheet filed by the CBI in the case on July 19 last year.The CBI is probing how Chidambaram, when finance minister in 2006, granted FIPB approval to a foreign firm, when only the Cabinet Committee on Economic Affairs (CCEA) was empowered to do it.The ED is also probing a separate money laundering case in the Aircel-Maxis matter, in which the Chidambarams have been questioned by the agency and their anticipatory bail is pending.The CBI and ED, in their replies to the anticipatory bail pleas, had told the court that custodial interrogation of both the accused was required since various new materials have surfaced after filing of the charge sheet, alleging that they were not cooperating in the probe.Chidambarams have come under the scanner of investigating agencies in the Rs 3,500-crore Aircel-Maxis deal and the INX Media case involving Rs 305 crore.