Chief of Defence Staff Air Marshal Alex Badeh told senior military officials from Nigeria and Cameroon meeting in Abuja on Friday that a "ceasefire agreement" had been concluded between the government and the insurgents.

Badeh's announcement came after a senior aide to President Goodluck Jonathan, Hassan Tukur, told AFP an agreement to end hostilities had been reached following talks, as well as for the release of 219 girls held captive since April.

But a precedent of previous government and military claims about an end to the deadly five-year conflict and the fate of the missing teenagers left many observers cautious.

Jonathan is expected to declare his bid for re-election in the coming weeks, and positive news about the hostages and the violence would likely give him a political boost.

Shehu Sani, a Boko Haram expert who has negotiated with the group on behalf of the government said he had "never heard" of Danladi Ahmadu, whom Tukur claimed represented the militants at talks.

Ralph Bello-Fadile an advisor to Nigeria's National Security Advisor (NSA), said the NSA has been inundated with fraudsters claiming to represent Boko Haram leader Abubakar Shekau."Government wants to negotiate but so far nobody has come forward who speaks for Shekau," he told a Chatham House conference in Abuja on Monday.

The Nigerian government's own security spokesman, Mike Omeri, also said that no deal had yet been reached on releasing the girls.The United States said it could not confirm whether a deal had taken place.

Tukur added he represented the government at two meetings with the Islamists in Chad, which were mediated by the country's President Idriss Deby.

"Boko Haram issued the ceasefire as a result of the discussions we have been having with them," said Tukur, adding that Ahmadu made the announcement on Thursday evening.

"They have agreed to release the Chibok girls," he continued, referring to the girls seized in northeast Nigeria on April 14, causing global outrage.

Leaders of the Bring Back Our Girls campaign, which has been pressuring the government to act, gave a cautious welcome to a possible release."We are monitoring the news with huge expectations," they said on Twitter.

Ndjamena refused to comment but security sources in the country said Chad, which Jonathan visited for talks with Deby early last month, had been involved in the discussions.

The source also said a ceasefire agreement was reached as well as the release of 27 hostages, 10 of them Chinese nationals, who were kidnapped in northern Cameroon earlier this year.

Cameroon announced on Friday that eight of its soldiers and 107 Boko Haram fighters were killed during fierce fighting in its far north region on Wednesday and Thursday.

A police officer told AFP that at least 30 civilians had been killed by Boko Haram before the military ambush.In Nigeria, unidentified gunmen on Friday killed eight people on a road near Shaffa village in Borno state, two local residents said, but it was not clear if the attack was by militants.

He made no reference to the Chibok girls and did not list the creation of an "Islamic state" in Nigeria's mainly Muslim north -- the core, unwavering Boko Haram demand since the uprising began.

The leader of the Nigerian Islamist extremist group Boko Haram, Abubakar Shekau dismissed Nigerian military claims of his death in a new video obtained on October 2 and said the militants had implemented strict Islamic law in captured towns.

Shekau has in a series of video messages since 2012 ruled out talks with the government and said northern Nigeria will never know peace until sharia (Islamic law) is strictly enforced.

Envoys from Nigeria's presidency have made similar ceasefire claims in the past, notably Jonathan's Minister for Special Duties Taminu Turaki, who led a so-called amnesty commission in 2013 that was tasked with brokering peace. But nothing materialised from Turaki's protracted negotiations. Shekau said that he never sent delegates to any talks and attacks continued at a relentless pace.