LAGOS — The arrest of a young Nigerian for trying to blow up a transatlantic airliner has again highlighted the strong streak of Islamic fundamentalism that pervades much of Africa's most populous country.
While the Nigerian government and Muslim authorities have condemned the failed bombing as an "isolated act", radical Islamist movements are thriving in a country where 12 northern states reintroduced Islamic law in 2000.
Umar Farouk Abdulmutallab, charged with trying to blow up a US passenger jet over Detroit, may appear an unlikely radical as the son of a powerful banker whose abiding passion as a teenager was English football.
But as a series of recent attacks on Nigerian government targets by Muslim hardliners shows, a combination of radical Islam and disaffected youths has proved a volatile cocktail on many previous occasions.
In July, mainly young militants of the fundamentalist Boko Haram sect which seeks to unite Muslims under a Caliphate carried out simultaneous attacks in four northern states.
The authorities' response was swift and brutal, killing at least 800 in a five-day crackdown and possibly twice as many according to Western intelligence sources.
In the local Hausa language Boko Haram means "Western education is a sin" making it increasingly attractive among the impoverished youth of the Muslim-dominated north.
The Nigerian government, while admitting that it has problems on its hands, insists that terrorism is alien to the country.
"One thing that I can tell you that we are not known for as Nigerians is terrorism," said Information Minister Dora Akunyil.
"We are not into terrorism; we may have several issues but definitely not terrorism. Our country abhors it."
But Nigeria's main armed rebel group in the oil-rich Niger Delta, MEND, said the government's show of surprise was misplaced, and accusing Abuja of allowing the situation in the north to fester as it kept its focus on the south.
Northern Nigeria, home to a Muslim majority while the south of the country is mainly Christian, is "fertile ground" for international terrorism, MEND said.
"The Nigerian government has persistently turned a blind eye to Islamic extremists coming from Northern Nigeria, choosing instead to focus and waste its resources on military hardware and troop deployment in the Niger Delta."
For decades after Nigeria's independence from Britain in 1960, there has been a long history of bloody clashes between ethnic and religious groups -- Sunni Muslims against Shiites, Christians against Muslims.
For the federal authorities which have been battling the insurrection in the Delta for years, the Islamists' rise in the north is an extra challenge adding to the traditional rivalry and mistrust between southern Christians and northern Muslims.
In the south especially people have not forgotten the 1967-70 civil war after the attempted breakaway of southeastern Biafra, which had been preceded by a slaughter of Christians in the north.
To complicate things, northern Nigeria borders Niger and Mali, a battleground for Al-Qaeda in the Islamic Maghreb, the former Salafist Group for Preaching and Combat whose activities have included kidnapping and killing westerners.
The threat from Islamist militants prompted Washington in 2007 to establish the US Africa Command (AFRICOM), headquartered in Stuttgart, Germany.
AFRICOM has faced controversy, with governments of various African countries fearing it was the beginning of increased US military presence in the continent.
But its commander, General William Ward, insisted during a visit to Algiers last month that the terrorist threat for north-central Africa's Maghreb and Sahel regions was real.