Lagos , Nigeria ( CNN ) -- Nigeria postponed its parliamentary election Saturday due to a `` terrible unfortunate emergency '' caused by the late arrival of voting materials , the head of the election commission said . Nigerians will instead go to the polls Monday , said Attahiru Jega , chairman of the Independent National Election Commission . `` We can not proceed with these elections if we want them to be free , fair and credible if there are no result sheets , '' Jega said . `` We can not bury our heads and say there are no problems . It is regrettable . It is unfortunate . It should not have happened . '' Jega said he takes full responsibility for the fiasco but he said a vendor that was supplying results sheets and ballots was unable to deliver them on time . The vendor , said Jega , cited the diversion of planes to carry relief supplies to earthquake-stricken Japan as the reason for the delay . Citizens of Africa 's most populous nation were supposed to vote Saturday for 360 House of Representatives seats and 109 Senate seats . They are scheduled to vote next Saturday in a presidential election and for state governors the following week . Before the logistical problems , the election , the most expensive in Nigeria 's history , had already been marred by riots , bombings and assassinations . `` The unprecedented levels of violence that have seen several people either killed , maimed , kidnapped or intimidated for political reasons pose the single most significant threat to the conduct of general elections , '' warned the Nigeria Elections Situation Room -- a forum of groups focusing on the upcoming elections . Human Rights Watch estimates at least 70 people have been killed in political violence in the run-up to the voting . The European Union described Nigeria 's 2007 elections as the worst they had ever seen anywhere in the world , with rampant vote rigging , violence , theft of ballot boxes and intimidation . Nigeria had hoped to gain a cleaner image this year . CNN 's Christian Purefoy contributed to this report .
The election commission chairman apologized for the incident . He said voting materials were late arriving from a vendor . Nigerians will vote on Monday instead .