* Jonathan meets governors over growing Boko Haram violence

* Bomb blast hit Abuja, 200 abducted girls still missing

* Violence also on the rise in religiously mixed Middle Belt

By Felix Onuah

ABUJA, April 24 (Reuters) - Leaders from across Nigeria appealed for a united front against Boko Haram on Thursday, saying the Islamist insurgents were waging war on Christian and Muslim Nigerians alike.

President Goodluck Jonathan held a security meeting with governors of 36 states straddling Nigeria's largely Christian south and mostly Muslim north to seek ways of ending the Islamists' five-year-old insurgency.

"We agreed that the Boko Haram war is not a religious war and therefore it's a war against all Nigerians and should be treated as such," a statement said after the meeting.

The insurgents abducted 230 schoolgirls on April 14 and most are still missing. On the same day, a bomb in a bus station on the edge of the capital Abuja killed 75 people, an attack for which Boko Haram claimed responsibility.

The two attacks showed the inability of the Nigerian security forces to protect civilians against Boko Haram, seen as the biggest security threat to Africa's top oil producer.

The insurgency by the group, whose name means "Western education is sinful" in the northern Hausa language, has killed thousands in the past two years.

Officials have long feared that Boko Haram, which wants to carve a breakaway Islamic state out of Nigeria, will harden religious divisions.

But while the group has repeatedly targeted Christians - blowing up churches or killing minority Christian ethnic groups in the north - the majority of their victims have been Muslims. The Islamists destroy churches, but also mosques.

"Both Muslims and Christians are being killed. Boko Haram doesn't discriminate against any person," Theodor Orji, governor of the southern Abia state, said after the emergency meeting.

"Boko Haram is not a religious war and people should not misrepresent it to be," Orji said.

Heightened Boko Haram attacks coincide with rising communal violence in the Middle Belt, where north and south meet, that has killed hundreds. Officials fear the Islamist insurgency will merge with this so far distinct conflict.

The military said on Thursday it had arrested gunmen who killed 40 people in two attacks on villagers in the east in the past week and they had confessed to being Boko Haram militants. The attack initially looked like Muslim Fulani herdsmen attacking ethnic Tiv Christian farmers.

(Writing by Tim Cocks)