Response of commercially available monitoring instruments to high-energy photon radiation was studied under the stored beam condition of a few milliamperes in the storage ring of the Synchrotron Radiation Source, INDUS-I, at Centre for Advanced Technology (CAT), Indore. The storage ring has a circumference of 18.96 m, where electrons at 450 MeV are stored for a few hours, during which the emitted synchrotron radiation is exploited for scientific research and other applications. Radiation environment near storage ring has bremsstrahlung photons of various energies (maximum 450 MeV). A study has indicated underestimation of dose by conventional radiation monitoring instruments by a factor of 2-4. Response after transmission of photons through massive shield was also studied, which indicated spectral degradation and good response by the survey meters.