Power to withdraw approval. 293C. Where the Central Government or the Board or an income-tax authority, who has been conferred upon the power under any provision of this Act to grant any approval to any assessee, the Central Government or the Board or such authority may, notwithstanding that a provision to withdraw such approval has not been specifically provided for in such provision, withdraw such approval at any time : Provided that the Central Government or Board or income-tax authority shall, after giving a reasonable opportunity of showing cause against the proposed withdrawal to the assessee concerned, at anytime, withdraw the approval after recording the reasons for doing so.