Mr Singh's series of tweets on Monday had questioned if the police move was authorised by Chief Minister K Chandrasekhar Rao. He had even asked the Chief Minister to resign if he had authorized the move.
The tweet by the senior leader, who was recently removed as the Congress in-charge of Goa and Karnataka after the party poor performance in the recent elections, read:
Telangana Police has set up a bogus ISIS site which is radicalising Muslim Youths and encouraging them to become ISIS Modules.digvijaya singh (@digvijaya_28) May 1, 2017
While no reaction came from Mr Rao, his ministers had issued scathing responses.
"The Telangana Police is widely appreciated (for its professional competence). He (Digvijaya) has made a false allegation that we created something, induced Muslim children and did something. He must prove it," state Home Minister Nayani Narasimha Reddy told reporters on Tuesday.
The state's info-tech minister KT Rama Rao too, had reacted sharply, saying as a former Chief Minister, Mr Singh should behave responsibly. The Telangana police had also responded, tweeting that the allegations could "lower the morale of the police fighting anti-national forces".
The former Chief Minister -- who was recently removed as the Congress in-charge of Goa after the party's poor performance in the recent assembly elections -- said he welcomes the investigation and will continue his fight against corruption.