Q&A: What are the implications of clashes in Nigeria?

(Reuters) - Clashes between Muslim and Christian gangs triggered by a disputed local government election have killed around 400 people in the central Nigerian city of Jos, the worst unrest in the country for years.

The city lies at the crossroads between Nigeria's Muslim north and its mostly-Christian south, but the conflict is about much more than religious beliefs.

Below are some questions and answers on what triggered the violence and what the implications are for Nigeria.

Q - How did the violence start?

A - Residents say demonstrators from the Hausa ethnic group began burning tires early on Friday after a rumor spread that their ANPP party candidate had lost the local government chairmanship race to the ruling PDP party.

The dispute awoke tensions which have simmered for decades in central Nigeria and violence quickly broke out between rival gangs armed with machetes and home-made guns, divided along political, ethnic and religious lines.

The tensions are rooted in decades of resentment by indigenous minority groups, mostly Christian or animist, who are vying for control of fertile farmlands with migrants and settlers from the Hausa-speaking Muslim north.

Q - Could the unrest spread?

A - Nigeria's 140 million people are roughly equally divided between Christians and Muslims and the two communities generally live peacefully together in both the north and south.

Ethnic and religious unrest in one part of the country has in the past touched off revenge killings elsewhere.

The Nigerian army has sent in reinforcements from neighboring states to impose a 24-hour curfew on the most troubled parts of Jos, capital of Plateau state, reacting more quickly than in the past in an effort to contain the unrest.

Previous flashpoints around Nigeria for ethnic and religious rioting have included Yelwa, also in Plateau, the southeastern city of Enugu and the second-largest city of Kano in the north.

Q - What does it mean for Nigerian stability?

A - Nigeria has experienced and weathered similar bouts of unrest in the past. Thousands have died in religious and ethnic violence since the start of the decade.

But the fighting comes as President Umaru Yar'Adua faces mounting criticism over the slow progress being made by his administration after 18 months in office.

Violence continues to plague the oil-producing Niger Delta, intermittent power supply remains a major hindrance to growth and a drawn-out cabinet reshuffle and weeks of delays to the 2009 budget have heightened political uncertainty.