The Police Ombudsman is unable to clarify how many members of the British military had links to the North West UDA/UFF.
Earlier this month a report published by Marie Anderson found there was evidence of "collusive behaviour" by some police officers.
Operation Greenwich examined 19 murders and two attempted murders carried out by the North West UDA/UFF between 1989 and 1993.
Ms Anderson said her investigation has established that several serving or former members of the military "had links to loyalist paramilitary organisations in the North West area during the period in question".
In her report five serving and former UDR officers are identified by cipher as having links.
They include Person A, J, K, V and Q.
However, the ombudsman's report appears to suggest "other" members of the military were also working with the loyalist gangs.
"This investigation has established that six other serving or former members of the military had links to loyalist paramilitary organisations in the North West during the period in question," Ms Anderson said in her report.
Mark Thompson of Relatives for Justice last night urged the ombudsman to clarify the figure.
"Can the ombudsman confirm for the families and for the public that that's 11 members of the UDR overall that were subject to her investigations?" he asked.
A spokesman for the Police Ombudsman said: "The ombudsman is mindful of the need to balance the right of the public to information about her investigations and the need to protect the identity of individuals whose actions are outlined in the public statement.
"In this context, she cannot provide any additional information beyond that which is already included in the public statement."
