The attackers are reported to have opened fire at the convoy.

Senator Ifeanyi Ubah is said to be "safe and in good condition" after the attack in Njikoka area, according to his Young Progressives Party.

The party said the senator's aides and police escorts lost their lives, but did not give the number of casualties.

Local reports quote an aide as terming it an assassination attempt.

Opposition presidential candidate Atiku Abubakar has condemned the attack in a tweet: