A leading Nigerian rights group is urging the UN Security Council to impose sanctions on Islamic extremists who abducted 276 schoolgirls, saying concern and condemnation are not enough.

The Socio-Economic Rights and Accountability Project said it is time for the council to “act decisively”. The cost of inaction is “too high to contemplate”, they said.

It comes as more experts are expected in Nigeria to help in the search, including US hostage negotiators.

Nigeria’s government belatedly accepted offers of help this week from the US, Britain, France, China and Spain amid mounting national and international outrage at its failure to rescue the girls abducted by Boko Haram militants from a north-eastern school on April 15.

The militants are threatening to sell the girls into slavery.

Yesterday’s call for action adds to the growing condemnation by Muslims in Nigeria and abroad against the Boko Haram terrorist network and its acts.

Former Nigerian military ruler General Ibrahim Babangida urged the country’s Muslims to rise up against the extremists sullying the name of Islam.

“Islam enjoins you to live peacefully with fellow human beings... Therefore, anybody who will come and smear our name, all Muslims should kick against that. Muslims should also do everything possible to stop this continued blackmail against the religion of Islam. We must prepare to fight it,” he said in an interview yesterday with the BBC Hausa Service. Hausa is the most popular language in northern Nigeria.

From Doha, Qatar, the International Union for Muslim Scholars condemned “the terrible crimes offensive to Islam” and said the actions of Boko Haram “are very far from Islamic teachings”.

It called on Boko Haram to immediately release the girls, saying that threats to sell them into slavery are against Islamic Shariah law. Boko Haram has said it wants to enforce Shariah law across the entire country though Nigeria’s population of 170 million is divided almost equally between Christians and Muslims. Shariah is pursued to varying degrees in most northern states.

In the Saudi city of Jeddah, the 56-country Organisation of Islamic Cooperation said it is mobilising for a meeting next week that will focus on groups like Boko Haram that are part of “the growing phenomenon of dangerous extremist groups who hijacked Islam and are committing crimes in the name of religion”.

Teenage hostages were ‘too scared to escape’

One of the teenagers who escaped from Islamic extremists who abducted more than 300 schoolgirls says the kidnapping was “too terrifying for words,” and she’s scared to go back to school.

Nineteen-year-old science student Sarah Lawan said that more girls could have escaped but they were frightened by threats to shoot them.

She said the girls were driven in a truck for hours after the gunmen took them from their school in the pre-dawn hours of April 15 before the truck stopped.

They were asked to get down and she and a friend bolted into the bushes.

Lawan spoke in a telephone interview from Chibok, the site of the mass abduction in northeast Nigeria.

She is among 53 students who escaped while 276 remain captive.

Boko Haram has staged many attacks in northeastern Nigeria over the years, a campaign of bombings and massacres that has intensified in recent times despite a strong military offensive.

Since May 2013 there has been a state of emergency in three northeastern Nigerian states covering one-sixth of the country.

Boko Haram has killed more than 1,500 people this year, compared to an estimated 3,600 between 2010 and 2013.