Intelligence Bureau has been asked to conduct the probe and find out whether the reports of CCTV cameras not functioning were true or not, a Home Ministry official said.
The Ministry will also seek a report from Uttar Pradesh government on how the CCTV cameras installed at Assi Ghat were not tested ahead of Modi's visit.
If the surveillance cameras were not working, it is a serious issue as the security of none other than that of the Prime Minister was involved, the official said.
Media reports suggested several security cameras at the venue and even some monitors in the control room were not functioning while Modi was at Assi Ghat cleaning the silt along the Ganga banks as part of the Swachh Bharat campaign drive.
Modi reached the Assi Ghat at 8.40am, followed by prayers. He then took up a spade to begin the Ganga clean-up drive as part of his 'Clean India' campaign.