A car bomb exploded along a busy roadway just outside a church on Sunday morning in a central Nigeria city, killing at least 38 people in the latest attack on a region beset by religious, ethnic and political violence, an official said.

The blast struck Kaduna, the capital of Kaduna state, leaving charred motorcycles and debris strewn across a major road in the city where many gather to eat at informal restaurants and buy black market gasoline. Nearby hotels had their windows blown out of by the force of the powerful explosion, which engulfed a group of motorcycle taxi drivers.

At least 38 people were killed in the blast, said Abubakar Zakari Adamu, a spokesman for the Kaduna state Emergency Management Agency. Others suffered serious injuries and were receiving treatment at local hospitals, Adamu said.

The explosion badly damaged the nearby All Nations Christian Assembly Church as churchgoers worshipped at an Easter service, the possible target of the bomber. Witnesses said it appeared the explosive-laden car attempted to go into the compound of that church before it detonated.

"We were in the holy communion service and I was exhorting my people and all of a sudden, we heard a loud noise that shattered all our windows and doors, destroyed our fans and some of our equipment in the church," Pastor Joshua Raji said.

Another witness, Augustine Vincent, said he was riding a motorcycle just behind the car when it exploded.

"God saw our heart and saved us," he said.

A second explosion struck the city of Jos, about 200 kilometres away in neighbouring Plateau state, on Sunday night, authorities said. Jos is another city where religious and ethnic violence has killed hundreds in past years.

Yushau Shuaib, a spokesman for the National Emergency Management Agency, said there were some injuries in the Jos blast, but had no other details. State police commissioner Emmanuel Dipo Ayeni said the cause of blast was still being investigated.

No group immediately claimed responsibility for either attack, though suspicion immediately fell on a radical Islamist sect known as Boko Haram.

Boko Haram, whose name means "Western education is sacrilege" in the Hausa language of Nigeria's north, is waging an increasingly bloody fight with security agencies and the public. More than 380 people have been killed in violence blamed on the sect this year alone, according to an Associated Press count.

The sect, employing suicide bombers and assault-rifle shootouts, has attacked both Christians and Muslims, as well as the United Nations' headquarters in Nigeria.

UK, US warned of Easter violence

The sect has rejected efforts to begin indirect peace talks with Nigeria's government. Its demands include the introduction of strict Shariah law across the country, even in Christian areas, and the release of all imprisoned followers.

Sunday's bombings also come as the British and U.S. governments warned their citizens living in the oil-rich country that violence was likely over the Easter holiday.

Kaduna, on Nigeria's dividing line between its largely Christian south and Muslim north, was at the heart of post-election violence in April 2011. Mobs armed with machetes and poison-tipped arrows took over streets of Kaduna and the state's rural countryside after election officials declared President Goodluck Jonathan the winner. Followers of his main opponent, former military ruler Muhammadu Buhari, a Muslim, quickly alleged the vote had been rigged, though observers largely declared the vote fair.

Across the country, at least 800 people died in that rioting, Human Rights Watch said. In the time since, heavily armed soldiers remain on guard on roadways throughout Kaduna. In December, an explosion at an auto parts market in Kaduna killed at least seven people. Though authorities said it came from a leaking gas cylinder, the Nigerian Red Cross later said in an internal report the blast came from a bomb.

In February, bombs exploded at two major military bases near the city, injuring an unknown number of people.

In his Easter speech at the Vatican, Pope Benedict XVI mentioned the ongoing violence in Nigeria. Catholic churches have been targeted in previous attacks.

"To Nigeria, which in recent times has experienced savage terrorist attacks, may the joy of Easter grant the strength needed to take up anew the building of a society which is peaceful and respectful of the religious freedom of its citizens," he said.