The agency has registered the case after gathering initial details of the probe from the CBI and other official channels and it is set to question few people including Rishi in this regard.
The ED, according to sources, is probing if these defence deals and those involved in the execution of the agreements had 'off the book' or overpriced transactions leading to generation of illegal funds which could have been subsequently laundered in other investment avenues.
The CBI has earlier questioned Rishi many times in connection with the alleged irregularities in the Tatra truck supply to the Army.
The ED has asked Rishi to produce documents related to the Tatra Sipox UK Memorandum of Understanding with the BEML which was inked in 1997 including the details of their financial statements and tax returns.
The Directorate will ask for similar documents from BEML and if the need arises, from the Defence Ministry, the sources said.
The probe agencies, according to sources, have found out that it was in 1997 that Tatra Sipox UK signed the truck supply deal with BEML which was in alleged violation of defence procurement rules which say that procurement should be done directly from original equipment manufacturer only.
The first agreement for the supply for Tatra all terrain truck used for the transport of soldiers, heavy machinery, missile systems among others was signed with the Czechoslovakia-based company Tatra in 1986.
In 1997, BEML started procuring trucks through Tatra Sipox UK, claimed to be the marketing arm of Tatra, in which Ravinder Rishi had a substantial stake.
The CBI has alleged that since Tatra Sipox UK was not the original manufacturer of these all terrain trucks, the rule that defence procurements should be made from the original manufacturer was violated.