The flats, whose allotments were irregularly revived to benefit certain property brokers, were allotted in 2007-08 but had lapsed owing to "non-payment of payments by the allottees as per rules," said a CBI source.
"Instead of canceling such defunct allotments, the accused DDA officials had irregularly revived them to benefit property brokers," said the source.
"The preliminary probe has shown that property brokers had contacted individuals whose allotments had become defunct and offered to make the payments on their behalf with the collusion of the accused DDA officials," the source added.
The flats were allocated in different parts of the city. The agency undertook searches in the city, Noida (Uttar Pradesh) and Gurgaon (Haryana) at the official and residential premises of the accused persons mentioned in the FIR.