Participants of a legacy talks forum hosted by the Archbishop of Canterbury at Lambeth Palace were told to keep the meeting "confidential", a whistleblower has said.
Among those reported to have been involved are officials from the Northern Ireland Office (NIO) and the Republic’s Department of Foreign Affairs, Sinn Fein strategist Sean (Spike) Murray and loyalist Winston Irvine.
Former Bedfordshire Assistant Chief Constable Jon Boutcher, who is leading Operation Kenova into the activities of allegedly British agent Stakenife, also attended the meeting.
Senior British military officers, Queen's University law lecturer Kieran McAvoy, former Victims' Commissioner Judith Thompson and the PSNI were also invited.
Victims' groups have reacted angrily to reports of the meeting, saying that they were not invited to take part.
An unnamed source who was present at the talks told BBC Radio Ulster's Nolan Show that participants were told not to disclose that the meetings had taken place.
The source said: "We were all meant to be confidential. If you got victims groups involved earlier on, that shuts one door. If you go down with politicians, another door shuts ."
However, the NIO has denied the talks were secret.
An NIO spokesperson said: "The UK Government is listening to people from all communities, victims and survivors regarding legacy issues, and is committed with our Irish partners to seek a way forward for everyone. We are not engaged in 'secret talks' with anyone."
Victims campaigner Kenny Donaldson, who represents Innocent Victims United, said: "Over the last couple of weeks a number of individuals who were part of that room have had cause to engage with me and with the organisation on a range of issues...and the process that came here to fore.
"Because this is not a one off meeting. Meetings off this nature have been going on since February.
"Not a word of any of this was said by those individuals. So it was intended to be kept extremely quiet."
The Northern Ireland Secretary Brandon Lewis has not confirmed if he was aware of the talks.
UUP MLA Mike Nesbitt, a former victims' commissioner, speaking to the Nolan Show, said: "Victims keep hearing people talking about processes that will be victim-centred and that expression is often honoured in the breach.
"Here is an example of a process that is not victim-centred because they are not even invited into the room."
The Sunday Life reports that the talks are also expected to recommend millions of pounds of funding for their arms length bodies.
Central to the discussions were how to deal with legacy issues and financial support for projects in loyalist and republican areas that have the backing of paramilitaries.
This, they argue, will help them move from criminality into established community roles. The money will come from the government’s £50million Fresh Start package to end paramilitarism.