Nigeria's President Goodluck Jonathan has rejected the idea of a swap of Boko Haram prisoners for kidnapped schoolgirls.
About 200 girls were kidnapped by the Islamist group a month ago.
After talks with Mr Jonathan in the capital Abuja, Britain's minister for Africa Mark Simmonds said the president had made it very clear there would be no negotiations that involved an exchange of the girls for Boko Haram prisoners.
On Wednesday there were reports the government was ready to negotiate with the militants although the day before the interior ministry rejected a swap.
The Islamist group posted a video on Monday offering to release them in exchange for prisoners held by the government.
Boko Haram, who are fighting for an Islamist state, stormed a secondary school in the northeastern village of Chibok on April 14 and seized 276 girls who were taking exams. Some have managed to escape, but about 200 remain missing.
The abductions have triggered a worldwide social media campaign under the Twitter hashtag #BringBackOurGirls, and prompted the United States, Britain, France and Israel to offer help or send experts to Nigeria.
Meanwhile the BBC reports soldiers in northeastern Nigeria deployed to deal with Boko Haram have shot at their own army commander.
Eyewitnesses said soldiers fired at his convoy in the city of Maiduguri.
Reports from northeastern Nigeria say local people have killed dozens of suspected Boko Haram militants in a series of ambushes.
The clashes occurred on Tuesday in a district called Kala-Balge in Borno State.