THE American senator who brokered the peace deal to end the Troubles has said it may be time to review the Good Friday Agreement structures.
Senator George Mitchell, who was was President Bill Clinton's special envoy to Northern Ireland, helped clinch the 1998 agreement.
Speaking ahead of this week's assembly election, he said he feared Brexit had reduced the prospect of compromise in the north.
He added that he hoped the fall-out from Brexit would not hinder the establishment of a new power-sharing government at Stormont.
"I believe that the European Union was an important factor that led the United Kingdom and Ireland to co-operate in establishing a process that led to the Good Friday Agreement and I think the UK being out of the European Union may reduce the prospect for further co-operation," he said.
"We recognised at the time, that by itself, the agreement did not assure peace or prosperity or reconciliation. It made them possible.
"So what I said at the time was that it would take many years and many difficult decisions by courageous leaders in Northern Ireland to attain those goals."
Senator Mitchell said the north's political parties would know themselves if it was now time for power-sharing by choice instead of a mandatory coalition.
"I think everyone anticipated that these arrangements were established to meet the problems and the needs of that time," he told Sky News.
"It is a normal part of the development of every society that over time institutions should be reviewed, processes should be reviewed."
