The threat call was received by Korutla MLA Kalvakuntla Vidyasagar Rao on his mobile yesterday, a day ahead of the CM's visit to Karimnagar.
"Vidyasagar Rao received a call on his mobile phone at about 6 PM on Tuesday from an unidentified person," a top police official said.
"The person, who used the Internet to make the phone call, threatened to kill the Chief Minister during his visit to Metpalli in Karimnagar district on Wednesday," he said.
The MLA handed over his mobile phone to Metpalli Sub- Inspector Babu Rao, to whom the caller repeated the same threat, police said.
Police have not yet identified the caller but said a probe was on.