Mr McCartney said;
“The use of Public Interest Immunity certificates in the case of the disappearance of 15-year-old Castlederg schoolgirl Arlene Arkinson is downright bizarre.
“It is completely unacceptable that the Secretary of State and NIO should be intervening to continue to deny a grieving family access to the truth of the death of their loved one.
“All of this raises even more serious questions about the Arlene Arkinson case which need answered.
“It emerged previously that the RUC Special Branch operated its own forensic service so the family need to know if any evidence was withheld from the initial investigation by Special Branch.
“We also had claims from a detective chief inspector from Kent who said he had been obstructed by the RUC while investigating the activities of Robert Howard.
“The Director of Public Prosecutions should now launch an inquiry to see if any evidence relating to the case was withheld.
“The Arkinson family have waited too long for the truth and should not have to put up with more obstacles being placed in their way.”