Nigeria on Friday claimed to have reached a deal with Boko Haram militants on a ceasefire and the release of more than 200 kidnapped schoolgirls but doubts immediately surrounded the purported breakthrough.
But a precedent of previous claims from the government and military about an end to the deadly five-year conflict and the fate of the missing teenagers left many observers urging caution.
Jonathan is also expected to declare his bid for re-election in the coming weeks, with positive news about the hostages and the violence likely to give him a political boost.
Multiple analysts cast doubt over the credibility of a man called Danladi Ahmadu, whom Tukur claimed represented Boko Haram at the two meetings in neighbouring Chad.
"I have never heard of such a man (Ahmadu) and if Boko Haram wanted to declare a ceasefire it would come from the group's leader Abubakar Shekau," said Shehu Sani, a Boko Haram expert who has negotiated with the group before on behalf of the government.
Ralph Bello-Fadile an advisor to Nigeria's National Security Advisor (NSA), told a conference onMonday that the NSA has been inundated with fraudsters claiming to represent Shekau."Government wants to negotiate," he told a Chatham House event in Abuja, "but so far nobody has come forward who speaks for Shekau."
Tukur said 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.
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.
The release of the hostages last weekend was "a first strong signal" from Boko Haram to prove their good faith, the source added but did not mention the schoolgirls.
- Discrepancies -
Ahmadu gave an interview broadcast on Friday on the Hausa language service of Voice of America radio in which he claimed to be the group's "chief security officer" and in charge of publicity.
He made no mention of an end to hostilities and was vague on details of the apparent talks, even claiming not to have met Shekau.
He also referred to the jihadi group as Boko Haram, a name that means 'Western education is forbidden' which was imposed on the Islamist radicals by outsiders. The insurgents themselves never use the term.
The group's known leaders have exclusively used the name Jama'atu Ahlis Sunna Lidda'awati wal-Jihad, which means "People Committed to the Propagation of the Prophet's Teachings and Jihad".
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.
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.
Turaki on several occasions maintained that he was negotiating with legitimate Boko Haram commanders, including Shekau's immediate deputies, and that a ceasefire was at hand.
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.
an AFP report