Gunmen have attacked the former head of Nigeria's central bank, Prof Charles Soludo, killing three policemen guarding him.

It happened at a campaign rally organised by Prof Soludo who is now running to become the governor of his native Anambra state in south-eastern Nigeria.

Eyewitnesses said the gunmen stormed the rally in Isuofia community town hall and opened fire on the gathering.

Three policemen were gunned down while a close aide of Prof Soludo was abducted.

It is not yet clear if the attack is connected to the gubernatorial election coming up in November.

In the last three months, more than 15 policemen have been killed in south-eastern Nigeria following attacks by suspected criminal gangs.

In some of the attacks, police stations were burnt down and guns and ammunition carted away.

Nigeria is currently in the grip of widespread insecurity especially in the north-east and north-west regions of the country.