Nigerian presidential contender Peter Obi of the opposition Labour Party said his supporters were on Saturday attacked and injured ahead of a rally in the commercial capital Lagos, a stronghold of the ruling party.
Previous elections in Africa's most populous nation have been fraught with violence between supporters of rival parties and a number of instances of political violence have occurred ahead of the Feb. 25 parliamentary and presidential vote.
"We cannot continue to tolerate attacks on members of the political opposition, often fuelled by the incendiary rhetoric of political leaders," Obi said in a statement, urging police to investigate.
It was not immediately clear who was responsible for the attack but local television stations showed several damaged cars carrying Labour Party stickers and injured supporters getting medical help at the rally venue in downtown Lagos.
Local police had no immediate comment.
At the rally, Obi told supporters he would reform the police to make it more professional, end the oil thefts that have hobbled production in the Niger Delta, and improve security to allow farmers to boost agriculture output.
Obi is leading in several polls but the race is expected to be tight. Young voters, frustrated by economic hardships, endemic corruption and unemployment, are Obi's main support base.
Obi will face Bola Tinubu, the former governor of Lagos and the ruling All Progressives Congress candidate, and former vice president Atiku Abubakar from the main opposition People's Democratic Party.
(Reporting by MacDonald Dzirutwe; Editing by David Holmes)
