A Nigerian court has charged eight suspects with allegedly taking part in a string of deadly bombings around the capital.

Prosecutors say the accused are members of the radical Islamist sect Boko Haram, which has claimed responsibility for several deadly attacks in Nigeria and has been blamed for dozens of others.

The suspects allegedly played roles in four separate attacks between March and July of this year that killed about 25 people. The most serious incident was the bombing of an elections office in the town of Suleija in April that killed 16.

The suspects entered pleas of not guilty during an appearance in a magistrates' court in Abuja Tuesday.

President Goodluck Jonathan has pledged to stop the wave of political and sectarian violence afflicting Nigeria, but so far with little success.

On Monday, assailants attacked a police station in the northeastern town of Misau, killing at least five people.

Boko Haram claimed responsibility for last month's bombing of the Abuja U.N. headquarters and a June bombing outside Nigeria's national police headquarters. The group wants to see Islamic law applied more widely across Africa's most populous nation.

Because of the violence, the U.S. embassy in Abuja has urged Americans to be vigilant, especially around places of worship and public gatherings.