At a press conference here, Kejriwal and Bhushan alleged that Vadra had bought property worth crores of rupees between 2007 and 2010 with an "unsecured interest free loan" of Rs 65 crore given by DLF.
They claimed that Vadra had secured the loan from DLF for companies floated by him and his mother with a seed capital of just Rs 50 lakh.
43-year-old Vadra, married to Priyanka Gandhi, was not in the capital and sources close to him said there was no reaction for the moment.
Congress spokesperson Manish Tewari said that these are "baseless, misconceived and utterly irresponsible" allegations.
"Coming ahead of Gujarat and Himachal Pradesh elections, it shows that the so-called civil society groups are morphing themselves as a political party but it is nothing more than a B-Team of the BJP," he told reporters.
A DLF spokesperson said the business relationship with Vadra is "completely transparent" and was conducted to "highest standards of ethics".
Kejriwal and Bhusan claimed an analysis of the balance sheets and audit reports of the five companies run by Vadra showed that they had no income from any legitimate business activity except the interest derived from the DLF's loans.