The list of decommissioned weapons handed over by paramilitary groups during the peace process could be published at a later date, Northern Ireland Secretary Owen Paterson has said.
There had been widespread criticism of the Independent International Commission on Decommissioning (IICD) when it announced on Monday that it did not plan to release a full inventory of decommissioned arms.
The detailed files on all the guns, munitions and explosives put beyond use by groups such as the IRA, UDA and UVF have instead been handed over to the US State Department in Washington for safe-keeping.
Mr Paterson said on Wednesday the IICD's decision must be respected but told MPs the files could be published when the British and Irish governments "together decide the time is appropriate". He told the Commons: "The IICD were quite clear as to why they did not publish an inventory. We would very much like to be in a position... to publish this data but the success of the IICD was its independence and they have the decision, it's entirely in their remit to decide where they put this information. This information is now in the hands of the Secretary of State in the USA and cannot be divulged without the prior agreement of the British and Irish governments."
Mr Paterson added: "We have to take the advice of these very experienced, independent professionals who pulled off an extraordinary task. I would pay tribute to General (John) de Chastelain (who led the inquiry) and his colleagues for what he did. If it is their professional opinion that it is not helpful today to publish that inventory, we have to take that advice seriously, as does the Irish Government.
"That is why the inventory has been placed with the American Secretary of State where it will rest, no-one will see it, until both the British Government and Irish Government together decide the time is appropriate."
William McCrea, MP for South Antrim, said the decision not to publish the inventory would affect public confidence, while his DUP colleague Jim Shannon, MP for Strangford, said there was "annoyance and anger" that the list was not made public.
During Prime Minister's questions, the DUP's Upper Bann MP David Simpson asked David Cameron: "Does the Prime Minister agree that details of all the weapons and explosives decommissioned in Northern Ireland should be made public as promised? And will he agree to have negotiations with the Irish government to move forward to the Americans to see that it happens here?"
Mr Cameron replied: "Well the point is the Independent International Commission on Decommissioning did not provide us with an inventory. They were an independent body and this was a decision for them to take, difficult I know as that is. They stated, and I quote: 'We would not wish inadvertently to discourage future decommissioning events by groups that are actively engaged today nor to deter groups that have decommissioned their arms from handing over any arms that may subsequently come to light'.
"This is difficult and we are all having to do in Northern Ireland and elsewhere in the world difficult things in order to bring conflict to an end and keep conflict to an end and that is what the independent decommissioning report was doing."