Liam Neeson has said the families of the so-called Disappeared were living in a cruel and inhumane limbo.
In an appeal for information about the whereabouts of seven IRA murder victims, the Star Wars and Taken actor said their relatives had endured decades of unthinkable torment.
"The pain caused by the murder of a relative is almost unimaginable.
"The pain of not knowing where that murdered relative has been secretly buried and the family denied the chance to properly grieve is almost unbearable," he said.
Seventeen people - 16 men and one woman - were kidnapped, killed and secretly buried by republican paramilitaries during the Troubles. To date, the remains of 10 people have been found after details were given to the Independent Commission for the Location of Victims' Remains (ICLVR) which was set up by the British and Irish governments after the 1998 Good Friday Agreement.
"While it is rightly acknowledged how far Northern Ireland has come as a result of the peace and political processes those seven families remain in a cruel and inhumane limbo," added the Hollywood star.
A key feature of the remit of the ICLVR is that information provided is held in complete confidence and can only be used for the location of the Disappeared. It cannot be shared with other agencies or for any other purpose such as progressing criminal proceedings.
Northern Irish-born Neeson has thrown his weight behind the campaign organised by the Wave Trauma Centre which has been supporting families of the Disappeared for over 10 years. In a joint statement with James Nesbitt of Murphy's Law fame - a long-standing Wave patron - both actors appealed for help.
"Where there has been co-operation the ICLVR has been very effective. The remains of Peter Wilson who disappeared in 1973 were recovered within two hours of the search commencing in November 2010. More can and must be done in the name of common humanity to help," they said.
The statement was issued to coincide with the launch of a new book The Disappeared Of Northern Ireland's Troubles which collates the personal stories of 14 of the families for the first time.