AFP/ Port Harcourt

Nigeria's ruling party on Monday won back control of the key oil-producing state of Rivers, official results showed on Monday, after rigging claims by the main opposition.

Nyesom Wike, from President Goodluck Jonathan's Peoples Democratic Party, won 1,029,102 votes, while Dakuku Peterside, of the All Progressives Congress (APC), won 124,896, the electoral commission said.

The APC, which previously controlled the state, described the result as "a rape of democracy" but the PDP said it was a "a reflection of the people's confidence" in them.

Rivers was a key battleground for both parties in the gubernatorial elections held on Saturday, given the oil and gas sector that is largely based in the southern delta region.

Tensions were high because outgoing governor Rotimi Amaechi had switched sides from the PDP to the APC in 2013 and become a vocal critic of Jonathan's government.

There were widespread claims from the APC of PDP irregularities in voting in the state at the presidential election held two weeks ago, leading to demonstrations and calls for a re-run.

Rivers voted nearly 95 percent in favour of Jonathan but the president lost the election nationally to the APC's Muhammadu Buhari, who secured the first opposition win in the country's history.

The state's information commission Ibim Semenitari said of the gubernatorial result: "What happened on Saturday was a rape of democracy. There was no election in Rivers.

"The PDP in connivance with INEC (Independent National Electoral Commission) and the security agencies merely wrote figures which they have churned out to the public," she told AFP.

She added: "We are going to challenge the results."

Local PDP spokesman Emmanuel Okha, however, said: "The people have spoken. We urge the APC to accept the results in good faith."