Arvind Kejriwal's office at his official residence received a call Monday from a person informing about threat of a possible attack on the Delhi chief minister, official sources said.
According to the sources, the person did not identify himself but said he was calling from Vikaspuri, a locality in west Delhi.
The caller said he has heard that somebody is planning to attack the chief minister, the sources said.
As the caller ID of the phone was not working, the number from which the call was made could not be identified, they added.
Caller ID installed at the office's landline telephone is not functional since May last year, the sources said, claiming that despite several reminders to the General Administration Department (GAD) of Delhi government it has not been fixed.
A senior police official said they were informed about the call by Personal Security Officer (PSO) of the chief minister and efforts are underway to identify the caller.
A couple of weeks ago, Kejriwal's office received an email threatening to kidnap his daughter. Subsequently, the accused was arrested.