More than 800 000 members of the minority Tutsi ethnic group and moderate Hutu as well as Twa were systematically slaughtered over 100 days between April and July 1994.
It is believed the fatalities were as high as 1 million in the worst genocide in recent memory.
An estimated 2 million Rwandans, mostly Hutus, were displaced.
Commemorations come ahead of the International Day of Reflection commemorated annually on April 7.
“We remember all those who were murdered and reflect on the suffering of the survivors, who have shown that reconciliation is possible, even after a tragedy of such monumental proportions,” United Nations (UN) Secretary-General, António Guterres, said.
He said countries had a fundamental responsibility to protect their populations from genocide, war crimes, ethnic cleansing and crimes against humanity.
“It is imperative that we unite to prevent such atrocities from occurring. The international community sends a strong message to perpetrators that they will be held accountable.”
The genocide in Rwanda ended when the Tutsi-backed Rwandan Patriotic Front led by Paul Kagame took control of the East African country.
Currently the chairperson of the African Union, he has been president of Rwanda since 2000.
Kagame has prioritised national development with the landlocked country of 12 million people developing strongly on key indicators, including the economy, healthcare and education.
– CAJ News