It has so far registered at least four FIRs to probe these cases, they said.
"The matter is under investigation with CBI, so the information cannot be provided under Section 8 (h) of Right to Information Act, 2005," said the office of the Commissioner of customs, Delhi, in reply to the query made under the transparency law.
The section bars disclosure of "information which would impede the process of investigation or apprehension or prosecution of offenders".
The department was asked to provide details of cases of missing gold from the vault under the Delhi customs at the airport.
To another query seeking details of gold lying in the vault, it said the information cannot be revealed due to security reasons.
"Further the matter (of missing gold) is under investigation with CBI as per direction of board (Central Board of Indirect Taxes and Customs) /Directorate General of Vigilance, the information cannot be provided under Section 8 (h) of RTI Act," the reply said.
The security of goods (gold and other precious items) is ensured as per the standard operating procedures issued by the competent authority, the customs department said, without sharing further details on those procedures.
Replying to another RTI query earlier, the Delhi customs had said over 23 kgs of gold worth more than Rs 6 crore had gone missing from its vault.
In June 2016, the customs officials had lodged an FIR in connection with disappearance of 11 kgs of gold from the vault.
Another case was registered in 2014 to probe instances of theft.
Similar cases were also reported to the Delhi Police on January 16, 20, April 30 and December 23, 2014 in which gold worth lakhs of rupees was replaced by a yellow colour non-precious metal.
An FIR was registered in June 2017 by the Delhi Police on the complaint of customs officials who said two gold chains and bangles, together weighing 298 gms, valued (then) at about Rs 8.83 lakh, were replaced with yellow-coloured non-precious metal.
The incident came to light when packets containing 1.27 kg gold, including the stolen chains and bangles, duly sealed at the instance of a court, were opened by the customs officials before a departmental committee as part of inventorisation proceedings.
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)