New Delhi, May 4 (IANS) Delhi Police Wednesday said they have received an anonymous call threatening to kill Prime Minister Manmohan Singh and his predecessor Atal Bihari Vajpayee. The mobile phone call was traced to Ghaziabad, Delhi's suburban town in Uttar Pradesh.

 
 According to police, the Delhi Police Control Room received the call Tuesday evening.
 
 "The number was traced to Ghaziabad but we were not able to trace the caller, as the address used to procure the SIM card was found to be fake,” a police officer said.
 
 Security agencies are conducting searches in the National Capital Region (NCR) to nab the caller.
 
 Delhi Police received another call Wednesday afternoon saying that a bomb was planted in Vasant Kunj area of south Delhi.
 
 The bomb disposal squad was despatched to the area, but found no explosives even after hours of searches in the area for hours.
 
 Police are trying to trace the caller's location, the officer said.