AAP has been accusing Lt Governor Najeeb Jung of trying to shield the officers found guilty by a CBI probe into the scam which was detected by Delhi Government's Anti-Corruption Branch in 2002.
"The inquiry commission will look into all the investigations and developments that have taken place so far in this case, including wrongful denials of sanctions to prosecute guilty officials and dereliction of duty in taking action against those involved in the scam," Delhi Home Minister Satyendra Jain said.
When asked whether Jung or Dikshit will be questioned, Jain said it will be up to the Commission to decide.
The CNG fitness scam surfaced in 2012 when ACB found that the Delhi government had lost over Rs 100 crore by awarding the contract to operate and maintain certification of CNG vehicles at the transport authority in Burari to ESP India Pvt Ltd instead of ESP USA.
In June, when the AAP government had directed ACB to reopen the case, the LG's office, rejecting crticism against him, had said the Justice Mudgal committee which had probed the case found no mala fide on the part of any government functionary.