The CBI's probe in the choppergate is stuck due to alleged deficiencies in the reference it received from the government.
A joint team, including two CBI officials and ministry of defence officials, will leave for Italy to seek case details.
"We could not file a regular case or a preliminary enquiry due to a technical problem," a CBI source said.
The source added, "The reference had just sought an inquiry into allegations as contained in media reports."
Meanwhile an Italian court has rejected India's request for case documents.