Nigerian elections cause riots. 16/04/2007. ABC News Online

Violent protests have erupted in Nigeria after the country's state elections.

Nigerians went to the polls on Saturday to vote for 36 state governors. But voting was marred by outbreaks of rioting, shootings and fires.

Local media is reporting that about 50 people have been killed in violence linked to electoral rigging.

Polling has been marred by voter intimidation, the theft of ballot boxes and even kidnapping of electoral officers.

Opposition supporters have been showing their anger as results show the ruling People's Democratic Party a clear winner.

Opposition supporters have turned out on the streets to protest and have burned buildings and blocked major city roads.

Opposition groups claim that vote rigging has been widespread and many are demanding fresh elections, while local news outlets are reporting that at least 50 people have been killed in violence linked to rigging.

There are also concerns that the violence and voting irregularities could be just a taste of what's expected at next weekend's presidential election.