Mumbai Police on Saturday received a message threatening to kill Prime Minister Narendra Modi, an official said.
The number from which the message was sent was traced to Ajmer in Rajasthan and a police team was sent there immediately to nab the suspect, said an official.
The WhatsApp message, received on the helpline of the traffic police in the early hours, mentioned a plot to carry out a bomb blast to target Modi, he said.
The investigators suspect that the sender is a mentally disturbed person or was under the influence of alcohol but further probe was on, the official added.
A First Information Report was registered under the relevant Bharatiya Nyaya Sanhita sections. The helpline of the Mumbai traffic police has received hoax threat messages many times in the past.