Where a registered dealer makes sales of any goods, other than those specified in Part B of Schedule IV, manufactured in his industrial unit situated in any Special Economic Zone, such registered dealer, may, for the purpose of determining his taxable turnover of sales, deduct under sub-clause (xi) of clause (a) of sub-section (3) of section 17 from his gross turnover of sales that part of such gross turnover of sales which represents the sales effected by such registered dealer from such industrial unit.