Suleja, February 20, 2012 - A bomb planted near an abandoned car exploded outside a church in the middle of a worship service on Sunday near Nigeria's capital, wounding five people amid a continuing wave of violence by a radical Islamist sect, authorities and witnesses said.

No one immediately claimed responsibility for the blast outside the Christ Embassy church in Suleja, a city near the nation's capital Abuja. However, the area has been targeted in the past by the sect known as Boko Haram - including the Christmas Day car bombing of a Catholic church nearby that killed at least 44 people.

The explosion happened just after 10am as the church began its service, Pastor Uyi Idugboe told journalists. Security guards at the church had noticed something suspicious by the abandoned car, prompting the pastor to call everyone inside the church before the service began, he said.

The bomb also apparently had been wrapped with a motorcycle chain, which sent metal shrapnel flying everywhere when the explosive detonated, witnesses said. The explosion tore away the engine compartment of the abandoned car and damaged four other vehicles nearby.

One person was seriously injured in the blast and taken to a local hospital, local police spokesperson Richard Oguche said. Another four people suffered minor injuries, said Yushau Shuaib, a spokesperson for Nigeria's National Emergency Management Agency.

Authorities began to put up roadblocks on Sunday afternoon to keep onlookers away and traffic snarled around the city.

While police continued to investigate, suspicion for the blast immediately fell on Boko Haram, a group that has been waging increasingly bloody attacks against Nigeria's weak central government.

Members of the sect have been blamed for killing at least 289 people this year alone, according to an Associated Press count. The group's leader says its campaign of violence also is aimed at avenging Muslim deaths and pushing for strict Shariah law across multi-ethnic Nigeria, a nation of more than 160-million people.

The sect's attacks, including those specifically targeting Christians, have widened distrust between the two faiths in Africa's most populous nation. Nigeria is largely split between a Christian south and a Muslim north, and most of Boko Haram's previous attacks have taken place in the north.

Bombs have struck Suleja in the past. During Nigeria's April election, a bomb planted at an election office in the city killed 16 people. Another bomb at a church exploded in July in the city, killing three people.

In nearby Madalla, another town in Niger state, a car bomb exploded outside St Theresa Catholic Church there, killing at least 44 people. Authorities have blamed all the previous attacks in Suleja on Boko Haram.

Meanwhile, authorities blamed the group for killing two people on Saturday in Nigeria's north-east. There, gunmen shot dead an Islamic cleric and a local politician in separate attacks, police said. - Sapa-AP