Modi, who Wednesday filed his nomination papers for Vadodara Lok Sabha seat, is also a contesting from Varanasi.
Mittal said the Congress had earlier complained about "the manner in which 1,000 prime locations meant for election publicity were taken over by the BJP and Modi in connivance with the authorities".
"The manner in which the nomination was filled by using the official machinery is also a glaring violation of the model code," he alleged.
