Nigeria’s oil city of Port Harcourt saw a heavy police presence on the streets on Saturday as voters went to the polls in gubernatorial elections, with early complaints of irregularities.

The state capital of Rivers was calm but officers were out in force screening vehicles and keeping watch, after large scale protests claiming rigging after the presidential election two weeks ago.

In the Rumuola area of the city, about 50 members of the All Progressives Congress (APC), which controls the state, staged a protest alleging fraud on the part of the Peoples Democratic Party.

“We are protesting that there should be no election in this area because they (the PDP) have changed the ballot papers and results sheets with fake ones,” protest leader Kingsley Wuolodi told AFP.

“This is the plot of the PDP to rig the election, so we are saying no election in this place.”

The APC claimed the PDP rigged the results of the presidential vote, which saw the state vote nearly 95 percent in favour of President Goodluck Jonathan.

Jonathan lost nationally to the APC’s Muhammadu Buhari.

Rivers is seen as a key prize for both sides because of the huge revenues from the oil and gas sector that is largely based in the state.