Nigerians on Friday marked three years since the mass abduction of nearly 300 schoolgirls by the armed Boko Haram group.

Activists rallied in major cities to urge President Muhammadu Buhari's government to do more to free the 195 schoolgirls who remain captive. Efforts to negotiate their freedom appear to have stalled.

"It is still a nightmare to me. It is still fresh as if it happened last night," said Rebecca Samuel, whose daughter Sarah remains missing. "The government is trying, but I believe they can do more than what they are doing."

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After a few of the girls escaped on their own, Nigeria announced the release of 21 of the Chibok schoolgirls in October after negotiating with the group. It said another group of 83 girls would be released "very soon".

No one has been freed since then, however.

The government this week said negotiations have "gone quite far" but face challenges. It refused to give details, citing security reasons.

Buhari on Friday said Nigeria is "willing to bend over backwards" to secure the schoolgirls' release.

"It is deeply shocking that three years after this deplorable and devastating act of violence, the majority of the girls remain missing," a group of six United Nations human rights experts, which visited Nigeria last year, said in a statement.



The experts also highlighted the fact that Boko Haram kidnapped thousands of other women and children in past years, most of whom also remain missing.



Amnesty International said it had documented at least 41 other mass abductions by Boko Haram since the beginning of 2014.

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The failure of Nigeria's former government to free the Chibok girls sparked a global Bring Back Our Girls movement and was a factor in Buhari's 2015 election win over the former president, Goodluck Jonathan.

"Today, the group has been degraded and is no longer in a position to mount any serious, coordinated attack, other than sporadic suicide attacks on soft targets," Buhari said.

"Even at that, their reach is very much confined to a small segment of the northeast."

Boko Haram's seven-year uprising has killed more than 20,000 people and driven 2.6 million from their homes. The Chibok schoolgirls have become a symbol of the fighting.