Agreement at the Stormont talks was "a sacred act" which honours those who have died and sows the seed for a better future, the Nobel Peace laureate, Mr Jose Ramos-Horta, told the ardfheis.
The East Timorese foreign minister in exile said he would be joining people "in spirit" in voting for the peace deal in May.
"What may seem as a concession today will be seen in the future as a first courageous step to the achievement of your goal," he said.
South Africa's African National Congress deputy secretary-general, Ms Thenjiwe Mtintso, said the Good Friday deal provided the foundation for a lasting peace. However, she said, "peace and justice do not reside in the attainment of a single agreement. The attainment of peace, justice and democracy resides instead in the transformation of all areas of society in which conflict and injustice have been able to flourish."
