Reconciliation is crucial in countries emerging from political turmoil, UN chief Ban Ki-moon said on Sunday at the opening of a UN Alliance of Civilizations forum.
The fourth annual forum, hosted this year by Qatar, includes delegates from several states touched by the Arab Spring revolts.
"In some countries (political) transitions have been peaceful. Others have seen bloody crackdowns," Ban said at the opening of the conference.
"But in all, reconciliation is essential for transformations to succeed," he added.
The popular uprisings that have swept across the Arab world over the last 12 months have brought down governments in Egypt, Libya and Tunisia, while Yemen's veteran leader Ali Abdullah Saleh, also targeted by protests, has agreed to stand down in February.
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But violence persists in Syria, where the UN says at least 4,000 people have been killed in the government's brutal crackdown on opposition demonstrators since the protest movement began in March.
The civilizations forum is being attended by more than 2,500 delegates, including political and business leaders, as well religious and youth activists.
Turkish Prime Minister Recep Tayyip Erdogan had been expected to attend, but was unable to travel after undergoing laparoscopic gastrointestinal surgery last month.
But in a taped speech Erdogan told the forum "as long as state terrorism continues in the Middle East... we will not see peace prevail across the world."
Ban later on Sunday participated in the inauguration of a Regional Centre on Transparency, Integrity and Combatting Corruption based in Doha.
"The establishment of this new centre comes at a historic time when the people of this region have voiced their emphatic rejection of corruption, and demanded that governments do more to combat this crime against democracy and to promote equitable development," Ban said in a statement received by AFP.
"Millions of ordinary people have said no to corruption. The international community must listen. Member states, private business, media and civil society, international and regional organizations -- all must heed the cry," he said.