The CBI, in a statement issued this evening, said it was "examining and verifying" the allegations.
The agency had received three complaints from Mishra, former Water and Tourism minister, in which he levelled charges of bribery and other irregularities against functionaries of Delhi Government, CBI Spokesperson R K Gaur said.
The Karawal Nagar MLA, who was yesterday suspended from the primary membership of the Aam Aadmi Party (AAP), also threatened to launch a hunger strike tomorrow if the party did not make public financial details of five AAP leaders' foreign trips.
A preliminary enquiry is the first step towards the registration of a case by the agency during which it gathers material to proceed with a regular case.
More From This Section
The agency might also refer the probe to the Anti- Corruption Branch (ACB) of the Delhi Government.
Speaking to reporters after coming out of the CBI office this afternoon, Mishra said his complaints referred to the alleged exchange of Rs two crore between Jain and Kejriwal, a Rs 50-crore land deal allegedly arranged for the chief minister's brother-in-law and about five AAP leaders' use of party funds on foreign trips.
He also dared Kejriwal to fight an election against him from a seat of his choice.
The former minister, sacked by Kejriwal on Saturday, had yesterday submitted documents to the ACB to back his allegations that Kejriwal had delayed a probe into a Rs 400-crore tanker scam in the city.