Police says they had found a powerful bomb planted under one of the seats of a stand for top officials at a political campaign rally in eastern Nigeria's Enugu State.

"It would have caused tremendous havoc," Enugu police spokesman Ebere Amaraeze told AFP by telephone on Saturday, adding that analysis indicated the effect would been "catastrophic" for 15 metres around.

The bomb had been placed in the stand reserved for state governor Sullivan Chime and other dignitaries, he said.

The police had launched an investigation but no arrests had been made, Amaraeze said.

The rally, staged by the People's Democratic Party (PDP) went ahead as planned.

Chime is seeking another four-year term as governor but has faced stiff opposition from political rivals. Party primaries last month resulted in litigation before he was declared the PDP candidate for the April elections.

Nigeria's influential northern politicians on Tuesday slammed recent primary polls held by political parties, saying they were tainted by violence, corruption and assassination of opponents.

Electoral fraud and violence have tanished past elections in Africa's most populous nation which has witnessed several bloody coups since it gained independence from Britain in 1960.