ABUJA (Reuters) - Nigeria's main opposition contender Muhammadu Buhari has picked southern Christian lawyer Yemi Osinbajo to be his running mate in elections set for February 2015, the party leader said on Wednesday.

Choosing a Christian from the south to run for the number two job alongside a Muslim northern presidential candidate fits a pattern in Nigerian elections of trying to balance ethnic and religious sentiments to maximise voter appeal.

President Goodluck Jonathan, a southern Christian who will seek re-election in the polls, picked his current vice president Namadi Sambo, a Muslim northerner, to run with him.

"I ask the people to remove religion from the electoral equation now that the tickets of both parties are mixed," opposition All Progressives Congress (APC) leader Bola Tinubu said in a statement.

"I ask you to select the ticket best able to end the downward slide that Nigeria has endured ... I ask you to remember that too many Christians and Muslims are poor."

Picking running mates from both ends of the country of 170 million people split roughly evenly between the two religions is unlikely to dampen the sectarian and ethnic sentiment that could be a flashpoint for trouble in Nigeria's most closely fought poll since the end of military rule in 1999.
Buhari's loss against Jonathan then caused parts of the north to erupt into violence in which more than 800 people were killed and 65,000 displaced.

How Africa's largest economy and leading energy producer conducts this election will be closely watched by investors.

The last vote in 2011 was deemed Nigeria's cleanest yet. The polls before it were marred by widespread ballot box stuffing, intimidation and sometimes completely falsified results.

Nigeria's Buhari picks southern Christian lawyer as running mate