CBI sources said Singh has assured them of providing more material about the alleged bribe offer very soon.
The agency has started examining the complaint received yesterday and may question Tejinder Singh in connection with the case, they said.
Sources said a call on whether to proceed with a preliminary enquiry or a regular FIR would be taken soon.
Tejinder Singh has refuted the allegations. He has also filed a defamation case against the Army chief and other officers.
The agency was waiting for a formal complaint from the Army chief regarding details of alleged bribe offer to initiate a formal probe into the matter referred to it by the Defence ministry. CBI officers had met him on Monday evening.
The Army Chief had claimed in media interviews that an equipment lobbyist had offered him a bribe of Rs 14 crore, a matter which he had reported to Defence Minister A K Antony.
The Ministry had then recommended a CBI probe into the allegation made by the Army chief.
After receiving reference from the Ministry, the agency had asked it to make available a complaint from Singh besides other details such as list of witnesses and supporting documents after which it would initiate its probe in the case.