Retro-amendment could only impose liability to pay tax and not interest for default of advance tax

IT : Where assessee claimed exemption under section 80-IA under a bona fide belief that claim of deduction under section 80-IA was available but said exemption was nullified by an amendment that came into force under Finance Act, 2007 with retrospective effect, assessee though would be liable to pay tax in view of retrospective amendment but it could not be held liable to pay interest under section 234B