* El-Rufai quoted as warning of violence in upcoming polls
* Nigeria faces closest poll since military rule ended
* Previous elections have triggered mob killings
By Camillus Eboh
ABUJA, Jan 27 (Reuters) - Nigeria's State Security Service (SSS) arrested the deputy head of the main opposition coalition on Monday over comments he is reported to have made warning of electoral violence in presidential polls scheduled for February 2015.
Nasir el-Rufai was quoted in the daily ThisDay as saying that the election was "likely to be violent and many people are going to die," as has happened in previous elections in Africa's most populous country and top oil producer.
"El-Rufai is with us. We are interrogating him over comments he made published by a newspaper on Thursday," SSS spokeswoman Marilyn Ogar said by telephone.
The elections are expected to be the most closely fought since the end of military rule in 1999 and Nigeria is bracing for politically orchestrated violence. Trouble is traditionally stirred up either to intimidate voters before the vote or to dispute the result after it comes in.
Rufai was also quoted as saying that if the election is rigged "and the alternative is left is to get power by force, that is the reality on the ground."
The SSS put out a statement the following day warning anyone issuing such "inflammatory" statements could face criminal prosecution. Rufia was unavailable for comment on Monday.
A spokesman for the All Progressives Congress (APC), of which Rufai is the second in charge, said he could not immediately comment.
INCREASINGLY HEATED POLITICS
The electoral commission declared on Friday that presidential and parliamentary elections would take place on Feb. 14 next year, with governorship elections a week later.
President Goodluck Jonathan's supporters are embroiled in a bitter dispute with other members of the ruling party over whether or not he should seek another term in office.
His critics say it would violate an unwritten rule that power should rotate between the largely Muslim north and Christian south every two terms.
The internal wrangling in his People's Democratic Party (PDP) has made the opposition's hand look stronger than ever.
Politics has become increasingly heated in Africa's top oil exporter since the four main opposition parties merged last February. Five state governors and dozens of lawmakers defected from the ruling PDP late last year.
Previous elections in Africa's second biggest economy have tended to be both violent and fraught with irregularities.
The one that elected Jonathan in 2011 was judged the fairest since the end of dictatorship, but disputes over it lead to some of Nigeria's worst ever post-electoral violence in which at least 500 people were killed. (Writing by Tim Cocks; Editing by Tom Heneghan)