LONDON — American envoy Richard Haass has returned to Belfast for a second attempt to quell simmering disputes which have periodically erupted into violence across Northern Ireland.

Haass, a former U.S. diplomat, was called in by the province's power sharing government to help resolve lingering disputes over flags, parades, and how to deal with the legacy of Northern Ireland's conflict.

All three issues have repeatedly tested the province's two-decade-long peace process, a series of agreements aimed at reconciling Northern Ireland's pro-British Protestants and pro-Irish Catholics after decades of bloodshed.

Haass failed to bring the parties to an agreement before Christmas, but saw enough potential to return for a second try.

In a message posted to Twitter Saturday, he said a "real opportunity for progress exists."