Janata Party chief Subramanian Swamy on Thursday levelled fresh allegations against Home Minister P Chidambaram, accusing him of delaying permission for the sale of Aircel to Malaysia-based Maxis in 2006 when he was finance minister so that his son Karti was financially benefitted. Swamy shot off a letter to Prime Minister Manmohan Singh seeking Chidambaram's resignation and asking CBI to include the names of the minister and his son in the FIR on Aircel- Maxis deal.