A Church of Ireland bishop who wrote to Boris Johnson over Brexit has said a no-deal departure could undermine the Good Friday Agreement.
Bishop of Clogher Rev John McDowell said he had not received a reply to his letter, sent in July, warning the Prime Minister of the potential for "incalculable damage".
"We should not underestimate the magnitude of what was achieved in 1998 and let that slip through our fingers," he told BBC Radio Ulster's Sunday Sequence.
Bishop McDowell said the border question had "a bit like the gun in 1998" been largely taken out of Irish politics by the agreement, but was now being brought back in.
There appeared, he continued, to be a lack of understanding about what that might unearth.
"Things have a habit of escalating and we don't know what they will escalate to," he added.
"As I said in the letter, the lava isn't far below the surface in Ireland and Irish history and sometimes it doesn't take much to break through the crust if it's clumsily handled."