The DoPT is the CBI's nodal department.
Under Secretary Sanjay Mehta, section officers Hemant and Vijay Pal and assistant section officers RK Arora and Mahendra Singh -- all belonging to the training division of the DoPT -- have been booked for alleged irregularities in the payment of over Rs 18 lakh, officials said.
The CBI also booked another person, Ashok, and private vendors Institute of Public Sciences, Institute of Public Administration, Kavita Ahluwalia, Kapil Book Store and Sahej Trading Corporation.
"It is also mentioned in the report that during random checking of sanction orders pertaining to the financial year 2016-17, three sanction orders issued by TFA Section found to be issued fraudulently without the approval of the competent authority," it said.
The DoPT said its preliminary enquiry indicates prima facie involvement of training department officials who have been subsequently named in the CBI FIR.