Abuja: Relatives of more than 200 schoolgirls held hostage by Boko Haram on Thursday called for their unconditional release, after Nigeria`s government ruled out a prisoner swap with the extremists.
Boko Haram leader Abubakar Shekau indicated in a video this week that he could release the 223 girls now held for more than a month in exchange for militant fighters in custody in Nigerian jails.
But Britain`s Africa minister Mark Simmonds said after meeting President Goodluck Jonathan on Wednesday that the head of state was adamant there "will be no negotiation that involves a swap".
Ayuba Chibok, whose niece is among the hostages, said the girls` detention was taking its toll on parents and families in their remote town from where the teenagers were abducted on April 14.
"For me, I want these girls released without any negotiations. Even if Boko Haram wants to request something from the government, let them request something else," he told AFP by telephone from Chibok.
"Let (Shekau) release these girls unconditionally," he added. The mass abduction -- and Boko Haram claims that the girls would be sold as slaves -- has led to global outrage and galvanised the international community to help Nigeria end the crisis.
US drones and manned surveillance aircraft have been deployed, the Pentagon said, while Britain was sending a spy plane and a military team to Abuja to work alongside French and Israeli experts.
In parliament, senators were quizzing security and military commanders before voting on a request by Jonathan for a six-month extension to a state of emergency in three northeast states.
Jonathan has called the security situation in the region "daunting" and said he was concerned by the mounting loss of life among civilians.
Boko Haram, which wants to create an Islamic state in Muslim-majority northern Nigeria, has been fighting an increasingly deadly insurgency since 2009 which has claimed thousands of lives.
More than 2,000 have been killed this year alone, most of them ordinary people.
Members of the lower House of Representatives were also expected to vote, with a two-thirds majority from members of both chambers required for an extension to be approved.
The state of emergency was first imposed on Borno, Yobe and Adamawa states on May 14 last year and extended in November, as attacks continued, particularly in hard-to-reach rural areas.
Yobe`s governor has already rejected extending the special powers. Borno and Adamawa are expected to follow suit.
All three are run by members of the main opposition party eyeing power at next year`s general elections.
Initial gains in forcing Boko Haram out of urban centres appeared to have been lost because of the continued strife, with questions raised about the military`s tactics and ability to curb the threat.
Analysts have said conventional means are ineffective against an enemy fighting a guerrilla war while more was needed to boost intelligence and even equip demoralised soldiers on the front line.
On Wednesday, Nigeria`s defence spokesman said troops fired shots as the local commander carried out an inspection in the state capital of Borno, Maiduguri.
The incident followed a Boko Haram ambush which killed four soldiers returning from patrol duties in Chibok. Other reports from the region said 12 were killed. Foreign powers involved in the rescue effort maintain that they are only providing logistical support to the Nigerians, who are leading the search in the northeast.
Nigeria, which has a sizeable army and spends massively on defence, has previously acted alone to try to contain Boko Haram and not requested any special assistance.
President Jonathan`s acceptance of foreign help has been interpreted as an admission it cannot go it alone, with concern that a largely localised conflict could spread across the wider region.
French President Francois Hollande is hosting Jonathan and the leaders of Benin, Cameroon, Niger and Chad at a security summit on the Boko Haram threat in Paris on Saturday.
US, British and European Union officials will also attend.
The United States has said none of its troops would be used on the ground.
But former presidential candidate Senator John McCain said Wednesday the Pentagon should consider acting unilaterally and send special forces to rescue the girls.
"We`re the best-trained, most professional military in the world, and if we know where these young girls are, we should go rescue them," he said, questioning Nigeria`s military capability.
US military officials said privately, however, that a rescue mission would be fraught with massive risks and dangers and that it currently was not deemed an option.