Nigeria is ready to talk to Islamist militants Boko Haram for the release of more than 200 abducted schoolgirls, a minister has told the BBC.
Boko Haram leader Abubakar Shekau said on Monday that captured girls who had not converted to Islam could be swapped for jailed fighters.
Special Duties Minister Tanimu Turaki said that if Shekau was sincere, he should send representatives for talks.
The girls were abducted last month from a school in north-eastern Nigeria.
A video emerged on Monday showing about 130 of the girls reciting Koranic verses.
Turaki - who is chairman of a committee set up by President Goodluck Jonathan to find ways of reaching agreement with Boko Haram - said that Shekau should send people he trusted to meet the standing committee on reconciliation.
Correspondents say that the government appears to have changed its stance in relation to talks, because it initially suggested there would be no negotiations with Boko Haram.
Government information agency Director Mike Omeri said late on Monday that the authorities would "use whatever kind of action" it took to free the girls, and that a military operation - with foreign help - was possible.