He was identified as Dr Narender Reddy, a resident of Kachiguda area here.
Reddy, who was sitting among the delegates, said 'Jai Telangana' in a rather feeble voice when Chief Minister Kiran Kumar Reddy rose to speak at the inauguration of the Asia-Pacific Ophthalmology Congress this evening. The President was on the dais then.
"We took him into preventive custody under section 151 of Criminal Procedure Code and later let him off on personal bail," Madapur DCP Yoganand said.
Reddy had retired as an assistant professor at Sarojini Eye Hospital here, and had been working at a private medical college in Mahbubnagar for the past few years, police said.