Colonel Bob Stewart has said it is "absolutely immoral" to consider that "people who have committed murder" in Northern Ireland should have the threat of prosecution taken away.
The Conservative MP served in Northern Ireland from 1971 and was one of the first responders to the Droppin Well bombing in 1982, which killed 17 people.
More top news
Bodies are being buried in backyards and overwhelming morgues as officials try to find another plot of land to lay them to rest.
Authorities have warned that the death toll is likely to rise as much of the building is yet to be searched.
The PM will sound out the possibility of new free trade agreements with Gulf states for once the UK has left the EU.