"I stand in solidarity with all those taking part in vigils today to demonstrate that the world has not forgotten the girls who were so cruelly abducted from their school 100 days ago," Xinhua quoted Ban as saying in a message on the vigils.
"I repeat my call for their immediate release and for an end to discrimination, intimidation and violence against girls whose only wish is to gain an education," he said. "Only by shielding them from harm and enabling them to realize their full potential can we usher in a better future for all."
About 270 girls from Chibok community in northeastern Nigeria's Borno state were abducted on April 14 by Islamist group Boko Haram, who threatened to sell the girls in a video. Specialist teams from several countries are searching for the girls, but scant progress has been scored so far.
According to UN, vigils will be held around the world on Wednesday to demonstrate solidarity with the Nigerian girls and their families. Supporters in Africa, Asia, Europe and the US are organising a series of campaigns, including lighting the candles, under the banner "Bring Back Our Girls" to maximise the visibility for continued global concern.
A wide coalition of organisations, including A World at School and its network of Global Youth Ambassadors and Girls Not Brides leaders, are spreading the campaign's message. In the Nigerian capital, Abuja, multiple events are organised by the Bring Back Our Girls group.
A World at School is also encouraging people to show their support of the initiative by signing a new online petition which calls for the safe return of the girls.
Gordon Brown, the UN special envoy for global education, is expected to send a petition to Nigerian President Goodluck Jonathan. The Chibok girls' families are also expected to sign the petition and offer their full support for the $23-million Safe Schools Initiative designed to pilot 500 safe schools in Nigeria, while bringing the country's government and business leaders together with the international community to ensure safe education for all children.
"Girls' rights should be taken seriously and they should be at school free of intimidation and violence. We will mark the 100 days by pledging to rebuild their Chibok school, and by calling for international support for safe schools across Nigeria," Brown said.
The UN envoy also urged the international community to stand in solidarity with the kidnapped schoolgirls and "never to abandon them", while "reminding people that we are in the midst of a global civil rights struggle."