Abuja (AFP) - Nigeria and the world marked the first anniversary of Boko Haram's abduction of 219 schoolgirls with protest marches, candlelit vigils and pledges of solidarity.
But as the teenagers entered their second year of captivity at the hands of the Islamist militants, Nigeria's incoming president said he could give no guarantees about their safe return.
Campaigners also used the focus on Tuesday's anniversary to highlight the situation in the girls' hometown should they be released, cataloguing the devastation wreaked by six years of conflict.
Muhammadu Buhari, who defeated President Goodluck Jonathan in elections two weeks ago, said there was a need for "honesty", with nothing seen or heard from the students since last May.
"We do not know if the Chibok girls can be rescued. Their whereabouts remain unknown. As much as I wish to, I cannot promise that we can find them," he said in a statement.
"But I say to every parent, family member and friend of the children that my government will do everything in its power to bring them home."
The comments by Buhari, who takes office on May 29, contrast with those from Jonathan, who was criticised for his response to the crisis in the restive northeast. Jonathan had vowed the girls would be found.
The military said last year it knew where the teenagers were being held yet ruled out a rescue mission because of the danger to the hostages.
- 'A bereaved community' -
A protest march, symbolically involving 219 schoolgirls, was held in Nigeria's capital, Abuja -- one of a number of anniversary events around the world.
In New York the Empire State Building was lit up in red and purple in honour of the missing girls. It was to remain illuminated until 2:00 am (0600 GMT).
Washington called for "all hostages held by Boko Haram, including these girls, to be released immediately without preconditions," State Department acting spokeswoman Marie Harf said.
Amnesty International said the Chibok girls' kidnapping was one of 38 in northeast Nigeria since the start of last year that had seen at least 2,000 women taken by the militants.
Testimony from women and girls who escaped the militants said they were subject to forced labour and marriage, as well as rape.
The UN and African rights groups also urged an end to Boko Haram's targeting of boys and girls, which has left at least 15,000 dead and some 1.5 million people homeless, 800,000 of them children.
UN Secretary General Ban Ki-moon led international pledges of solidarity with the girls and their families, who described coming to terms with the abduction as like a bereavement.
Chibok elder Enoch Mark, whose daughter and niece are among the captives, said no events were planned in the town, as it was still in "perpetual fear" of Boko Haram, despite the presence of troops.
"The last year has been a period of sadness, emotional torment and hardship. It has been a year of mourning. We are a bereaved community that has lost 219 daughters," he told AFP.
Buhari was now their hope of finding the girls, dead or alive, he said, pointing to the former army general and military ruler's success in putting down an Islamist rebellion in 1984.
Chibok campaigner Ayuba Alamson-Chibok said immediate support, including from abroad, could be given to the remote community in Borno state, which lacks drinking water and medical facilities.
"Those people (living in the town) really, really need help," he added.
- '#365DaysOn' -
The mass abduction brought the brutality of the Islamist insurgency to worldwide attention and prompted a social media campaign, #BringBackOurGirls, demanding their immediate release.
On Tuesday, supporters from New Zealand to the United States again posted online, using the hashtags #365DaysOn, #ChibokGirls and #NeverToBeForgotten.
Boko Haram, whose name translates roughly from the Hausa language as "Western education is sin", has attacked numerous so-called "secular" schools, their teachers and students since 2009.
Rebecca Ishau, one of the schoolgirl marchers in Abuja, said the government should make education safe for everyone in Nigeria "as a matter of priority".
Britain's former prime minister Gordon Brown, now the UN special envoy on global education, wrote in The Guardian newspaper the girls were kidnapped "simply because they wanted to go to school".
The campaign was "the most iconic fight of a freedom struggle. The fight will be won some day. No injustice can last forever. But for the sake of these girls, it must be won soon," he said.
Boko Haram fighters stormed the Government Secondary School in Chibok on the evening of April 14 last year, seizing 276 girls who were preparing for end-of-year exams.
Fifty-seven escaped soon afterwards. Boko Haram leader Abubakar Shekau has since said the remainder have all converted to Islam and been "married off".