A spokesman for Boko Haram tells the Guardian exclusively that the Islamist group says it will not stop deadly attacks until country is ruled according to dictates of Allah.
"We will consider negotiation only when we have brought the government to their knees," the spokesman, Abu Qaqa, said in the group's first major interview with a western newspaper. "Once we see that things are being done according to the dictates of Allah, and our members are released [from prison], we will only put aside our arms – but we will not lay them down. You don't put down your arms in Islam, you only put them aside."
Qaqa, whose name is a pseudonym, said the group's members were spiritual followers of al-Qaida, and claimed they had met senior figures in the network founded by Osama bin Laden during visits to Saudi Arabia.
The interview comes a week after Boko Haram claimed responsibility for Nigeria's single deadliest terrorist attack, which killed 186 people in the northern city of Kano.
In an audio message posted on YouTube on Friday, the group's current leader, Abubakar Shekau, threatened to bomb schools and kidnap family members of government officials.
"If [security forces] are going to places of worship and destroying them, like mosques and Quranic schools, you have primary schools as well, you have secondary schools and universities, and we will start bombing them."
Shekau rejected calls for a negotiated peace from President Goodluck Jonathan, who on Thursday called for the shadowy sect to step out of the shadows and engage in dialogue.
Nigerian officials have voiced hopes for a negotiated settlement with "moderate elements" of the group. "Under the circumstances, if you look hard enough, you can find moderate elements you can communicate with," General Andrew Azazi, the national security adviser to the president, told the Wall Street Journal on Friday.
Western diplomats say Boko Haram has splintered and the hardliners leading the factions responsible for the wave of violence that has killed some 250 people this year appear to have rejected any suggestion of dialogue.
The Guardian was able to contact Abu Qaqa through an intermediary from the group's home state. The go-between has been in contact with the group since its inception, and met with its founder, Mohammed Yusuf, several times before he was killed in 2009. For most of the interview he used a voice modulator, but local journalists confirmed that his undisguised voice matched recordings of previous interviews.
Qaqa said Shekau and others had travelled to Saudi Arabia for training and funding. "Al-Qaida are our elder brothers. During the lesser Hajj [last August], our leader travelled to Saudi Arabia and met al-Qaida there. We enjoy financial and technical support from them. Anything we want from them we ask them."
He said recruits from neighbouring Chad, Cameroon and Niger had joined the group. A recent UN report said weapons from Libya may have been smuggled to Boko Haram and al-Qaida in the Islamic Maghre via Chad, Niger and Nigeria.
Security officials and diplomats in Abuja said they had no evidence of a link with al-Qaida in Saudi Arabia, but an official confirmed that "elements of Boko Haram have made contact with external groups". The extent and frequency of that contact was unknown, the official said.
In the decade since it first appeared, Boko Haram has graduated from crude driveby attacks on beer parlours to bombing security buildings in the northern Muslim heartland. Its most audacious attack targeted the United Nations building in the capital, Abuja, killing 25 in August. In recent weeks, Christians institutions have increasingly come under fire. A Christmas Day bomb attack on a packed church just outside the capital claimed almost 40 lives.
But Qaqa said the rights of the country's 70 million Christians, who represent half of Nigeria's population, "would be protected" under the group's envisioned Islamic state. "Even the prophet Mohammed lived with non-Muslims and he gave them their dues." But he said everyone must abide by sharia law: "There are no exceptions. Even if you are a Muslim and you don't abide by sharia, we will kill you. Even if you are my own father, we will kill you."
Speaking fluent but non-native Hausa, the lingua franca across the Sahelian belt on the cusp of the Sahara desert, he said: "It's the secular state that is responsible for the woes we are seeing today. People should understand that we are not saying we have to rule Nigeria, but we have been motivated by the stark injustice in the land. People underrate us but we have our sights set on [bringing sharia to] the whole world, not just Nigeria."
Sharia law is already in place across 12 states in the Muslim-majority north. Few believe the group's radical ideology has traction in Nigeria's mainly Christian south, which is also home to millions of Muslims and has so far been out of the group's reach.
Raising his voice for the only time during the interview, Qaqa denied reports that some governors in northern Nigeria paid the group monthly allowances in exchange for immunity from attacks. "May God punish anyone that said so," he said, before adding that the group has popular support in the north.
"Poor people are tired of the injustice, people are crying for saviours and they know the messiahs are Boko Haram. "People were singing songs in [northern cities] Kano and Kaduna saying: 'We want Boko Haram'," Qaqa said, describing how the group can blend into the communities in which it operates. "If the masses don't like us they would have exposed us by now. When Islam comes everyone would be happy," he said.
Diplomats say Nigeria's security services are belatedly attempting to gain control of the situation, which was previously dismissed as an internal, northern squabble often fuelled by politicians with personal grievances.
"There is an ongoing review of all security agencies," the presidential aide Ken Wiwa said. "This is a relatively new phenomenon in Nigeria and the administration is working hard to improve its capacity to respond. There are various other initiatives which will be implemented but this is as much a political as a security issue."
An official said Nigeria's central bank was involved in measures aimed at strangling the group's external funding sources, including speeding up a cashless economy.