The families of the Omagh victims will tell the Northern Ireland chief constable of their fears a deal will be cut with the bombers over the outrage.
Sir Hugh Orde is to meet the Omagh bomb victims' families
Michael Gallagher will be on the relatives' delegation for talks with Sir Hugh Orde and his senior officers.
The Real IRA was blamed for the 1998 attack, which killed 29 people.
Mr Gallagher said relatives were concerned the lack of convictions was because the government was afraid they would later have to free the bombers.
"We are slowly coming to the view that the reason people are not being put behind bars is because it is only a matter of time before there will be a deal between the Irish and British governments and the terrorists that bombed Omagh," he said.
"That again has been the history of what we have seen recently - it would be an embarrassment for the government that if those responsible for the Omagh bomb had to be released.
"From the governments' point of view it is better to have those people not in prison so that you don't have the embarrassment of releasing the Omagh bombers."