Islamist militants have released a video purporting to show some of the Nigerian schoolgirls whose abduction has triggered international indignation.

Chanting verses from the Koran and wearing hijabs, the girls – around 130 are seen – are said to have converted to Islam.

The claim comes from Boko Haram leader Abubakar Shekau who also says on the video that none will be freed unless jailed Boko Haram prisoners are released.

That demand has been rejected by Nigeria’s government.

In Lagos, hundreds of people marched to call for the return of the more than 200 girls seized from a secondary school in the northeastern village of Chibok.

Some women activists threatened to undress at the scene of the kidnapping unless their protest produces results.

“The girls must be rescued now and that should be done while they are still alive and that is the essence of this protest,” said activist Joei Odumakin.

“At the end of 14 days of the nationwide protest, if nothing is done, God forbid, all of us are going to protest half-naked inside Chibok.”

France, Britain, the US and other countries have offered help in finding the girls, who Boko Haram have previously threatened to ‘sell’.