The hundreds of Nigerian schoolgirls abducted a year ago by the group Boko Haram deserve a major, sustained rescue effort, says a Nigerian lawyer who urges far more global attention for the wider crisis in the country.

"Every day of captivity for these girls is a dark day in their lives and their parents' lives. It's harder to keep hope alive," international human rights lawyer Emmanuel Ogebe of the U.S.-Nigeria Law Group told CNA April 14.

He said not enough is being done to find the girls. In his view, intervention of an international coalition is needed.

"(T)he world hasn't aligned itself similarly to counteract Boko Haram, as they are doing with ISIS," he said, referencing the Islamic State terrorist group, to which Boko Haram has reportedly pledged allegiance.

On April 14, 2014, Boko Haram militants abducted nearly 300 predominantly Christian girls from a secondary school in Chibok. Several dozen escaped, but there are 219 girls believed to remain in captivity.

Escapees have reported rape, forced marriage, forced labor and abuse. The group International Christian Concern said some of the abuse was intended to coerce them into rejecting Christianity.

Boko Haram leader Abubakar Shekau claimed the abducted girls have all converted to Islam and have been married, Agence France Presse reports.

The abduction of the Chibok girls prompted a social media campaign using the hashtag "#BringBackOurGirls." Participants in the campaign included U.S. First Lady Michelle Obama, human rights activist and Nobel Prize laureate Malala Yousafzai, and more than a dozen Hollywood personalities.

But while the social media effort may have raised awareness, Ogebe said concrete action to rescue the girls has been lacking.

"There needs to be massive deployment of intelligence assets and available technology to look for the girls, and this needs to happen on a sustained basis. We cannot wait for every anniversary before we have a fresh hashtag campaign," he said.

The lawyer also pointed out that the kidnapping of the school girls was far from an isolated incident.

According to Amnesty International, at least 2,000 women have been abducted in 38 mass kidnappings in northeast Nigeria since the start of 2014. Boko Haram is believe to have killed at least 15,500 people since 2012.

Ogebe said Boko Haram's "onslaught" has continued despite Nigeria's elections and the regional efforts of the military.

He pointed to what he sees as a double standard in the reaction to violence by Boko Haram and the reaction to the actions of ISIS: the latter have drawn strong global condemnation and airstrikes from an international coalition.

While the beheading of about 21 Coptic Christians in Libya by Islamic State militants inspired "global outrage," Ogebe said, there was little reaction to Boko Haram's September 2013 mass beheading of 170 people, 150 of whom were Christians.

Both groups have declared their own Islamic caliphate and follow strict interpretations of Islamic law. Last month, reports were released indicating that Boko Haram had pledged its allegiance to ISIS.

Ogebe said the international community appears not to have a consistent approach, "in spite of the fact that both terror groups are now aligned."

"What clearer evidence do we need that this is the same ideology at war?" he asked.

In addition to global cooperation to rescue the girls, Ogebe also said that international humanitarian assistance from religious groups is "desperately needed."

"This really has the potential for a huge crisis. And we don't have any of the major humanitarian groups working in Nigeria," he said.

On April 14, Nigerians marked the anniversary of the Chibok kidnapping with protests and vigils.

Muhammadu Buhari, Nigeria's president-elect, has said it not known whether the girls can be rescued and their whereabouts are unknown.

"As much as I wish to, I cannot promise that we can find them," he said, while pledging that his government will do "everything in its power to bring them home."