Colonel Aminu Iliyasu said the suspects "include an army major and four policemen, a serving commissioner and a local lawmaker in the state".

All were arrested in the southern state of Rivers on Saturday during the presidential and parliamentary elections, he told reporters in the state capital, Port Harcourt.

Other suspects were "thugs recruited by politicians to cause disturbances during the polls", he added.

Iliyasu accused the Rivers state governor Nyesom Wike of attempting to bribe the army to compromise the polls in favour of his Peoples Democratic Party (PDP).

Iliyasu said that "500,000 naira ($1,500, 1,200 euros) was found on the major while 2.5 million naira was found with the policemen, believed to have been given to them by agents of the governor," he said.

Saturday's elections, which had been postponed for one week because of logistical problems, saw widespread delays at polling stations, as well as intimidation and violence.

One election volunteer was killed by a stray bullet in the Rivers state, where some staff of the Independent National Electoral Commission and even police were held hostage before being released unharmed.

Iliyasu said some of those arrested were found in a state government vehicle on Saturday with bundles of ballot papers meant for the vote.

He said Wike had launched a "campaign of calumny against the army" and accused them of bias and partisanship.

The suspects were being handed over to the police while the arrested army major would be disciplined internally, he added.

Rivers is the heart of Nigeria's oil and gas industry and has a long history of election-related violence.

Sixteen of the 53 people killed in violence linked to the vote last weekend were in Rivers, according to civil society monitors.