The governor of Nigeria’s south-eastern state of Anambra, Peter Obi, has been re-elected, the electoral commission has announced.

The result was rejected by all other parties, who said their supporters were disenfranchised because their names did not appear on the electoral register.

The Nigerian government has admitted there were some irregularities during Saturday’s election.

A BBC reporter in Anambra says security is being stepped up across the state.

Mr Obi represents an opposition party, the All Progressives Grand Alliance. Official results show his party won in 13 out of 21 local government councils.

Earlier, the Nigerian Minister of Information, Dora Akunyili, admitted there had been some “hiccups” during the election.

Many polling stations opened hours late and there were confrontations as voters discovered their names were not on the electoral register.

Gangs of youths intimidated and harassed voters, and there were reports of ballot boxes being snatched from several polling stations, the BBC’s Caroline Duffield reports from Lagos.

The elections have been closely watched as an indicator of how general elections next year will be run, our correspondent adds.